Participation in the Triune God and Communion Ecclesiology

Abstract

Overcoming the harmful side of dualism is one of the key contemporary challenges. Theologically, this has meant a holistic turn in trinitarian theology. The article aims to bring relevant features of the patristic understanding—especially St Augustine’s—into dialogue with the contributions of Luther and Bonhoeffer to trinitarian ontology. The thesis of this article is that Augustine’s theological heritage can promote an ecumenical understanding of participatory trinitarian thinking which combines both Western and Eastern approaches. I suggest that it can provide valuable insights for the current theological discussion. The approach of the Augustinian tradition, which focuses on the concept of relation and develops its connection with substance, and the approach of the Greek Fathers and their theology of the primacy of the person of the Father are brought into dialogue. It is suggested that in Luther’s and Bonhoeffer’s further development of Augustinian theology, the understanding of the Trinitarian communion as a dialectic between person and community in love can in a constructive way overcome both ecclesial individualism and rigid collectivism and form a horizon for a holistic ecumenical theology for today.

1. Augustinian Trinitarian Ontology in the Theology of Luther and Bonhoeffer

The Study of Trinitarian Ontology—An Ecumenical Challenge

Encountering the modern global problems (ecological crisis, new technologies, etc.) also from the perspective of Christian faith and thought has meant a holistic turn in trinitarian theology. The ecological catastrophe is challenging anthropocentric hubris and calling us to rethink the relational character of the human being as the image of God. New challenges continue to arise: artificial intelligence, digitalisation, and transhumanism pose questions to the understanding of human dignity. More reflection is required. We therefore focus here on ontology, the core of reality. Theologically this means looking afresh also at the trinitarian theology. A key patristic figure especially for the Western tradition is St. Augustine (354–430), who developed further the trinitarian theology of the Cappadocian fathers (Basil of Caesarea, Gregory of Nyssa, and Gregory of Nazianzus). A key question is how we can discover the most influential theologians in the West and in the East as a resource for a more holistic and ecumenical theology that combines the vertical and horizontal dimensions of life.

In his article, Patristic Trinitarian Ontology (2012), Giulio Maspero refers to Jean Daniélou’s view that trinitarian ontology “…shows us that the very foundation of existence, the foundation of reality, the form of everything because it is its origin, is love, in the sense of interpersonal community. The foundation of being is a community of persons… The foundation of being is communion”. (Maspero 2012, p. 211, quoting Daniélou 1968, pp. 52–53). Daniélou was one of the most important representatives of nouvelle théologie (de Lubac, Balthasar, Congar, Daniélou), which rehabilitated sacramental ontology and understood itself as a movement of ressourcement (Boersma 2009 (2012 paperback), pp. 289–90). Ecumenically, Luther and Lutheranism from their perspective also promoted a return to the sources, to the Bible and the Fathers. This included trinitarian theology, sacramentality, and communion ecclesiology. These are also important Augustinian and Eastern theological themes. One of the most important modern Lutheran theologians whose thinking reflects this approach was Dietrich Bonhoeffer.

The thesis of this article is that Augustine’s theological heritage can promote an ecumenical understanding of participatory trinitarian thinking which combines both Western and Eastern approaches. I suggest that it can provide valuable insights for the current theological discussion. In the limited scope of this paper, I use systematic analysis as a method to bring relevant features of the patristic understanding—especially St Augustine’s—into dialogue with the contributions of Luther and Bonhoeffer to trinitarian ontology. I aim to unfold a little further the historical and contemporary relevance of these questions to the contemporary ecclesial and cultural discussion. This could also be seen as a contribution to the approaching 1700th anniversary of the Nicene Creed 2025.

2. Two Ways of Interpreting Trinitarian Ontology: Relation and Substance vs. Relation and Person

Schematically, two approaches to interpretation are taken in historical-dogmatic studies of trinitarian ontology. The Augustinian tradition focuses on the concept of relation and develops its connection with substance. The other approach takes as its premise the Greek Fathers and their theology of the primacy of the Person of the Father. However, a harmonisation of these readings has been suggested (Cf. Oberdorfer 2001, p. 241; Anatolios 2011, p. 241; Maspero 2012, pp. 212–13).

We begin with Augustine, the father of the Western trinitarian tradition. For example, Khaled Anatolios maintains that Augustine continued to develop the theological vision of the trinitarian unity of being, as Athanasius and Gregory of Nyssa taught. From a Lutheran and ecumenical perspective, it is important to note the primacy of Christ in the development of trinitarian doctrine. This is linked with the epistemological principle that it is impossible to encompass the being of God within the confines of human knowledge, but that we can consciously and thankfully be incorporated into the trinitarian life (Anatolios 2011, p. 241; cf. from a philosophical point of view Kany 2007).

Bernd Oberdorfer emphasised that the trinitarian theologies of the Cappadocians and Augustine were long seen not as exclusive alternatives but as two approaches to the same Nicene trinitarian faith. This included the idea of the primacy of the Father, although this was emphasised differently. There were also other important differences between these two approaches, revealing that the meaning of the dogma could be theologically explained in different ways (Oberdorfer 2001, pp. 107–28). St Augustine himself clearly intends to represent the Nicene faith (Cf. On the Trinity V/3,4 for St Augustine’s interpretation of homoousios, cf. Behr 2020, pp. 153–66).

More radically than the earlier Greek Fathers, St Augustine draws conclusions in De Trinitate about the theological theory of knowledge, anthropology, and redemption based on God’s self-revelation. He further develops the Cappadocians’ observation that there are traces of God’s triune being (vestigia Trinitatis) to be seen in creation. To demonstrate this and promote faith in the triune God and its consequent understanding, Augustine’s thought applies analogies of the Trinity which can be found in created reality. These reflections provide the basis for a trinitarian ontology. It seems unnecessary to juxtapose the Eastern doctrine of the Trinity and Augustine’s conception and to claim that the latter is predominantly characterised by the dominance of unity (Oberdorfer 2001, p. 196).

In Augustine’s theology, the category of “relation” constitutes the unique status of each trinitarian Person. It allows him to posit essential, not accidental, definitions of God which differ in each Person. He writes in De Trinitate:

“…it is demonstrated that not everything that is predicated of God is predicated according to substance, as He is called good and great according to substance, or anything else that is predicated of Him in respect to Himself, but that some things also are predicated relatively, i.e., not in respect to Himself, but in respect to something which is not Himself; as He is called the Father in respect to the Son, or the Lord in respect to the creature that serves Him; and that here, if anything thus relatively predicated, i.e., predicated in respect to something that is not Himself…”.

(De Trinitate XV, 15.3.5., cf. Maspero 2023, pp. 242–48)

The relation between Father and Son is clear, but the relation of the Holy Spirit is not self-evident. Yet the expression “gift of God” (Ap.t. 8:20, John 4:10) regarding the Spirit is relationally structured. Augustine considers that the Spirit as a gift is “a certain unspoken fellowship [ineffabilis quaedam patris filiique communio] of Father and Son”. In the Spirit, as a gift Father and Son donate themselves reciprocally to each other. The Spirit is the hypostasised fellowship or unity itself. The Spirit is “the mutual love of Father and Son, in which they love each other reciprocally” (XV/17,27, cf. also VI/5,7). At the same time, Augustine does not forget that the Scripture also teaches: “God [and not the Holy Spirit] is Love” (cf. XV/17,27). The semantics of fellowship, unity, and love connects the intratrinitarian position of the Spirit and the Spirit’s economic function: the outpouring of the divine love in human hearts and, consequently, love of neighbour, unity, and the communion of the Church. The concept of love provides Augustine with a bridge in formulating creaturely analogies of the Trinity (Oberdorfer 2001, pp. 111–12).

Augustine does not abandon the idea of the monarchy of the Father, but the idea that the Son also “sends” the Spirit is in tension with the Father’s principality. Augustine’s solution is that the Father gives the Son not only divinity but the ability to be the (co-)sender of the Spirit: “But from that, from whom the Son has his divinity—he is, after all, God from God—from him did he receive that the Holy Spirit goes out of him too” (XV27, 48; co. 26,47; 17,29). There are no two principles in God that would destroy the unity of God (cf. V/14,15). It is clear Augustine is representing the Nicene faith here. He argues in depth for the equal divinity of the Father, the Son, and the Holy Spirit (Oberdorfer 2001, pp. 112–13).

Nevertheless, Augustine tends to formalise the intratrinitarian relations more than the Cappadocian Fathers. His category of relation is disconnected from the concrete relations between the Father and the Son, and the Father and the Spirit. He understands “relation” more generally as a category that defines the specific characteristics of the intratrinitarian dynamics: the reciprocal relations between the hypostases, the triune Persons. He therefore also names the relation between the Son and the Spirit, not only the relations of origin between the Father and the Son, and the Father and the Spirit. Moreover, he sees the concept as also “deriving” from the Son and the economic sending relationship to the immanent Trinity, which increases formalisation, the tendency to form a coherent logical system (Oberdorfer 2001, p. 113).

Yet the dominant feature of St Augustine’s trinitarian theology is communion and the concept of love. It is not only a person who is revealed in the revelation but the constitutive relations between the Persons of the triune God (Oberdorfer 2001, pp. 113, 117). The strength of this approach is that it allows expression to be given to the participation of the triune God in the communion of love, and to the indwelling of the Trinity in the Church and the faithful as the basis of their unity in love. The monarchy of the Father belongs to the constitutive elements of this theology, although the principle is less dominant than in the Cappadocian approach (Cf. On the Trinity XV/14,15). For example, Gao Yuan summarises in his doctoral thesis Augustine’s understanding of deification like this: “This deification through redemption and grace does not make humans a hypostasis of the Trinity, nor does it stop at the beatitude of humanity, but rather includes a real transformation of humanity into a better form by participating in the triune spiritual life through the bond of the Holy Spirit” (Yuan 2015, p. 227).

It must also be acknowledged that Augustine’s approach fails to underline the importance of the apophatic character of theology as much as the Eastern tradition. Nevertheless, he does not abandon the idea of the apophatic mystery of God. On the Trinity begins with the words: “The following dissertation concerning the Trinity, as the reader ought to be informed, has been written in order to guard against the sophistries of those who disdain to begin with faith, and are deceived by a crude and perverse love of reason” (I/1,1).

Gregory of Nyssa is one of the mediating figures between the East and West. This is already evident in his understanding of the sending of the Spirit, in which the Father sends the Spirit through the Son (Oberdorfer 2001, pp. 90–91). Gregory understands substance as a reference to the ultimate ontological reality. Theologically, this refers to the triune communion of Persons in which each Person is in a free relationship of gift with the Others. Each One is themselves through the Other. This ontological understanding resulted in a new theory of knowledge. A trinitarian gnoseology corresponds to a trinitarian ontology, as Giulio Maspero has pointed out. In classical philosophy, the logos was understood as a necessary relationship. The corresponding theology was identified with the ontology of thought (Aristotle). Yet the trinitarian Logos does not imply merely an ontology of thought, but an ontology of thought and liberty. The transcendent God is a free Person. A human being can approach the mystery of God in his thought only through love, which God gives himself in a free, personal relationship. Apophatism understood in this context is the gnoseological expression of this centrality of relation and person. Given the ontological gulf between God and creation, theological knowledge is possible only through gift. Despite God’s self-gift, the freedom of God or his mystery remains inviolate. Trinitarian gnoseology means that knowledge becomes an act of filial communion. The primacy of the Father is interconnected with the primordial character of communion (Maspero 2012, pp. 223–25).

In Gregory’s trinitarian ontology, energeia, or activity, is critical for an understanding of the inseparable distinction of immanence and economy, or God’s being and act. It is possible to recognise the three Persons in the unity of divine action as separate Persons in a reciprocal relationship with the Others. This means that being must be reinterpreted from the perspective of a relationship. God “is one precisely because He is triune”. He can be known only in adoration and praise. Accordingly, because of the relational and personal depth of being, the apophatic dimension becomes a fundamental element of theology. The trinitarian dimension unites essence and existence by connecting intelligence and will through relation and person (Maspero 2012, pp. 226–28).

The result supports the idea that a trinitarian ontology that underlines not only one substance, but the importance of communion, person, and relation is also possible in the Western tradition, and is even fundamental for the understanding of the dialectic between God’s act and being. It is therefore plausible to search for such a trinitarian ontological orientation in later Western theology too. For example, Luther’s theology is significantly influenced by the Augustinian tradition.

3. Luther’s Trinitarian Ontology and the Understanding of Participation in Faith

Finnish Luther research, with its emphasis on the presence of Christ in faith, unfolds the ontological, sacramental, and mystical dimension in Martin Luther’s (1483–1546) theology. As Jonathan Linman, for example, pointed out, this approach, with its communal and communion ecclesiological implications, can contribute much to the development of the Lutheran and Christian proclamation. It provides deep insights into a context in which isolation, alienation, and almost non-existent communal life overshadow human life. The approach has broad ecumenical potential (Linman 2007, pp. 197–99; Hinlicky 2010, pp. 292–93). Paul Hinlicky sees ecumenical convergence and “a new evangelization of post-Christian societies in Euro-America” as “the one and same question” (Hinlicky 2010, p. 300). It is a common Christian quest in the East and West, and North and South, to find a constructive balance between the individual and communal aspects of Christian faith and life.

Academically interesting from this point of view are the studies that further develop the discoveries of the Finnish Luther research regarding the understanding of the gift and pneumatology in Luther’s theology. Examples of these are Kärkkäinen (2004), Saarinen (2016), and Ruokanen (2021).

In his article Hat Luther eine trinitarische Ontologie?, which analyses Luther’s early Christmas sermon In natali Christi. Joh. 1,1–14, WA I, 20–29 (1514), Tuomo Mannermaa concludes that Luther “no doubt” represents, at least in a certain phase of his creative period, a theological or trinitarian ontology that was influenced by Augustinian thought. He demonstrates four implications of this ontology crucial to Luther’s theology (Mannermaa 1994, pp. 44–46). In using the term “ontology”, Mannermaa’s basic question is “What kind of ontological character does the being of God in a Christian have?” (Mannermaa 1994, p. 43; Peura 1990, pp. 88–105).

The first implication of Luther’s trinitarian ontology is that he never mixes theology with philosophy as such. He believes Aristotelian philosophy can serve theology when viewed from a theological perspective, that is, in its theological relevance. Mannermaa concludes that Luther’s sermon formulates a certain theological doctrine of being (Mannermaa 1994, pp. 46–47).

Secondly, Mannermaa denies that Luther wishes to represent essentialist ontology or “substance ontology”. The Reformer understands being ultimately theologically, in the light of faith in God. The basis of this theological ontology is the Holy Trinity. Processio verbi out of God is God himself. This means that being thus understood implies a constant production of the Word. The presence of God in faith is neither a thing nor an entity. It is an actual reality, which is being, esse. Aristotelian philosophical concepts are used, but they are “baptised”. Mannermaa refers to the analysis of Ludger Oeing-Hanhoff concerning St Augustine’s criticism of Aristotle’s doctrine of categories. Augustine understands the Spirit essentially as knowledge of the self. God expresses himself in this knowledge, which is an “image and representation of himself”. This representation is pure, not more understandable as an accidence of substance. Therefore, in God, the Word, which represents him completely, is a complete image of him (Mannermaa 1994, p. 47 quotes Luther (WA 1,27,22–26) and L. Oeing-Hanhoff, Ontologie, trinitarische. HWP, Bd. 6, S. 1201).

Thirdly, this early theological ontology, which is based on a trinitarian understanding of being, has both a relational and an ontological aspect. The Father produces the Word, who is in a certain sense another and related to the Father. However, this production of the Word as the Other is also simultaneously the being of God himself. “God is in producing the Word… The movement, actus mobilis in itself, is the being of God Himself”. Relatio and esse mutually indwell. This interpenetration of relation and being has a fundamental significance for Luther’s understanding of the participation of the human being in God in faith (Mannermaa 1994, pp. 47–48).

Fourthly, the essential identity of the Word with God the Father is crucial in the context of an understanding of the incarnation. The inner Word of God takes the form of the external Word: he incarnates. “Because the divine being is the Word, in the incarnated Word the being of God himself encounters us. When the faith is now participation in Christ, in this faith necessarily takes place a kind of partaking in God or deification of the human” (Mannermaa 1994, p. 48).

Mannermaa explicates participation more closely as a consequence of Luther’s trinitarian ontology in the light of the final part of the 1514 Christmas sermon. “The trinitarian Word has become flesh, so that flesh became Word.” This does not mean the human being ceases to be human; nor does it mean that God ceases to be God. As at Chalcedon (451), the Word is paradoxically both fully God and fully human. The human being is made nothing before he or she can be deified. Mannermaa does not hold that Luther replaces the philosophical concept of substance, “ens in se”, with a theological one. He maintains Luther uses both philosophical and theological concepts. The philosophical concept expresses the theological content (Mannermaa 1994, pp. 49–50).

Luther points out that the incarnation of the Word does not happen substantialiter: the substance of God or of the human being does not change. They remain to be entities in themselves. In other words, the use of philosophical terminology does not mean that God is understood as physical, nor are God and humans integrated in a pantheistic way. In Luther’s use, the concept of “substance” is intended to safeguard the difference between the Creator and creation. In their unio, God and human remain realities existing in themselves, substances of their own (Mannermaa 1994, p. 50).

According to Mannermaa’s analysis, Luther bases his strong understanding of participation on the Aristotelian ontological theory of knowledge. There is an important limitation in the theological use. The union of knowing and the known, love and the loved one, cannot be understood substantialiter. Only when intellectus and affectus are oriented towards their objectives are they related, like matter seeking form. In relation to their objectives intellectus and affectus are, from a certain perspective, nothing. However, they become something existent (Seiende) as soon as they attain the objectives of their longing (cf. WA 1,29.22–27; Mannermaa 1994, pp. 51–52, 58; WA 2,201,20–21).

The result of this theological ontological theory of knowledge is the following: “So is God as the objective of salvation the essence itself (ipsa essentia) of the saved, without which the saved would be nothing, but when they reach him, they become something out of the possible. Therefore, God is the Act”. The relation to God is the basis of being in God. In conclusion, the relational and the ontological aspects belong together and are in each other (Mannermaa 1994, pp. 52–53).

Accordingly, Luther presents a trinitarian ontology in which classical substance ontology is reinterpreted within the trinitarian framework with a soteriological focus as a theology of faith and self-giving love. In his own way, he develops the tradition of a specific Christian or trinitarian ontology which unites the relational and ontological aspects as well as act and being, person and community, in the understanding of the Trinity, and, based on this, ecclesiology and participation in salvation. Doing this, he clearly develops Augustine’s and the Cappadocians’ thoughts about participation in the trinitarian life. An example of a theologian who takes up this task further in the modern ecumenical context is the famous Lutheran theologian Dietrich Bonhoeffer.

4. The Dialectical Unity of Act and Being—Bonhoeffer’s Trinitarian Ontology

Bonhoeffer (1906–1945) formulates a theological epistemology and ontology in the post-Kantian framework in his habilitation Act and Being: Transcendental Philosophy and Ontology in Systematic Theology (1930). He had already begun to work towards this end in his doctoral thesis Sanctorum Communio: A Dogmatic Study of the Sociology of the Church (SC 1927). In SC, he clearly sees the ecclesiological point of orientation in the tradition of Augustine and Luther which understands the Church as a communion of faith and love:

The positive unity of faith is concretely supported by the fellowship of love. Unity must be fought for as long as it is not there. The weapon of the Christian Church is love. It will always be an act and a demand of the Christian love to aim towards unity. We are not permitted to allow the great thought of Augustine that the caritas is the bond of unity of the Church to be lost. Of course, a divinely ordained unity is here presupposed, and only on the basis of this is the human deed meaningful (Bonhoeffer 1986, pp. 135–36. See also Karttunen 2018a, 2018b).

Ontologically and epistemologically, Bonhoeffer unfolds this vision in Act and Being (cf. Bonhoeffer 1988, p. 23). The book may be regarded as Bonhoeffer’s small systematic theology.

Bonhoeffer first analyses the problem of act and being in the context of autonomous philosophical reflection from the perspective of transcendental philosophy and ontology. The first conclusion is that a “genuinely transcendental approach” should be capable of being philosophically realistic: there is a being that is independent of the human consciousness. The specific question concerns the reality of God’s revelation. The “genuine” approach should thus include concepts of being. Secondly, it should be capable of showing how the revelation in its relation to the human consciousness can maintain its character as an act. No transcendental-idealistic approach is appropriate, but a “genuinely transcendental” one is needed (Bonhoeffer 1988, pp. 48–52). “Genuinely” refers to the realistic understanding of being, independent of consciousness. Yet the subject ought to be aware of this being: a realistic epistemology and ontology are interconnected. The second conclusion is that a “genuinely transcendental” model leaves being to be free and unobjectifiable, and the Dasein is thought of in relation to this being (Bonhoeffer 1988, p. 36).

A “genuine ontology” sees being as an a priori condition of thought. In the transcendental approach, the limits are set by reason itself. In genuine ontology, the being itself is more independent, but it somehow belongs to the power of the thinking “I”. In both cases, a closed system understands itself from itself. Philosophy as an autonomous thought with its own logic cannot leave room for revelation. If it did, it would be a Christian philosophy (Bonhoeffer 1988, pp. 71–72).

According to Bonhoeffer only thought which “is” of truth, obedient to Christ, can be posited as truth (Bonhoeffer 1988, p. 74). He thus theologically applies the classical idealistic principle, which Augustine and Luther had already used, in which only Spirit can understand Spirit. Human reason must be illuminated by the light of faith in Christ through the Holy Spirit (For Augustine’s and Luther’s understanding of the illumination see Karimies 2017).

In the theological part of his book Bonhoeffer analyses the problem of act and being in the context of the revelation. He shows how the solution can be found by connecting revelation, the Church, and faith. He first analyses the contingent character of revelation and the understanding of revelation as an act. Bonhoeffer underlines that the question of theology is not so much the immanent Trinity, i.e., God in God’s self, but the coming of God into the world in God’s giving of God’s Word in God’s covenant, that is in the economical Trinity. God has freely committed God’s self to human beings living amid the historical reality. God is there, present, not eternally unobjectifiable. We might even say we can “have” God and understand God in God’s Word in the Church. If this is to be the genuine understanding of the freedom of God, we cannot understand the revelation only as an act, but as a need, being, and ontological conceptuality (Bonhoeffer 1988, p. 85; cf. Sanders 2010, p. 40). The concept of “revelation” already implies that something is revealed and known. The revelation of God in Christ is somehow known (Bonhoeffer 1988, p. 86).

The problem for “critical ontology” in theology is to express God both as an object of knowledge and as unobjectifiable. Revelation is present in existing reality, and faith has a positive content: the presence of Christ in the Church for the congregation as the revelation of the triune God. This knowledge should not be systematic phenomenology, but it is “itself based on and suspended in a being-already-known” (“einem Erkanntsein gründet und aufgehoben wird”). Bonhoeffer thus understands transcendence personally, as a relationship between persons. God is the “absolute Person” and, as an object of faith, a “triune Person” (Bonhoeffer 1988, p. 104; Karttunen 2004, pp. 127–28).

According to Bonhoeffer, the being of the revelation and the existential encounter of people is possible only when the being of the revelation is understood transsubjectively in the Church as an interpersonal community. The dialectic of act and being in the revelation of God transcends all existing entities. The ultimate problem of “critical ontology” is the “pure ontological unfolding of revelation” which rejects both the understanding of the revelation as an existent being and as a non-existent act (Bonhoeffer 1988, pp. 102–3).

“Genuine ontology” presupposes an epistemological concept that encounters the existence of a human being but is not fixed to actualism, acting without being, and an object of knowing which is genuinely the human being’s opposite in a way that threatens and limits his or her mode of existence. The knowledge is based on being known and suspended in it. The object can be an existent being only in the ultimate qualification of being and non-being itself. It is the basis of my being, my existence, prior to me. In this being the knowledge must be repeatedly suspended. The preached revelation of God in Christ, the self-giving triune Person, is thus the object of our knowledge (Bonhoeffer 1988, pp. 103–4).

This epistemology has anthropological consequences and presuppositions. Bonhoeffer especially points to two: (1) the existence of a human being must be encountered; (2) it must be understood to be in continuity. The reality of the revelation is thus “being which constitutes the being (the existence) of human beings” (seiendes Sein selbst). This makes possible the new being of Christians. The being is “the triune divine Person”, Christ himself, who exists as the church community. “Being in Christ” is therefore also “being in the Church”. This implies that there are existential acts that are as constitutive as the being that constitutes these acts. Act and being are thus in a reciprocal and mutual relationship. Only thus can a “genuine ontology” be articulated. The being of the existent person is not in the power of the knowing subject. According to Bonhoeffer, such a genuine ontology makes genuine theological concepts of being possible: the essence of a human being, their knowledge of God, and theological anthropology (Bonhoeffer 1988, p. 105).

Bonhoeffer connects this genuine ontology to his understanding of the Church as the right place in which to understand the “Dasein”, the human being. Autonomous human knowledge cannot be the basis of the understanding of the Dasein. This is theologically justified because the revelation of God in the cross and resurrection is contingent. The revelation of God’s reconciliation with sinful humanity cannot be deduced from any logical premise. The truth of the revelation and being in this truth can be revealed only “from the outside”. This sets us in the truth and thus gives us an understanding of the Dasein. Only from the perspective of the revelation can other ways of understanding the human being be seen as unsatisfactory and outside the truth. Bonhoeffer sees being’s relation to the act of the revelation as the equivalent of being in the Church as a theological-sociological category (Bonhoeffer 1988, pp. 106–7).

The revelation takes place in the Church, by the Church, and for the Church. It is either a present proclamation of the death and resurrection of Christ, or it is not genuinely contingent. Contingence can be encountered only in present historical reality. In a contingent understanding, proclamation is determined by the future; in a systematic understanding, it is determined by the past. The Christian proclamation is qualified by eschatology and predestination, which paradoxically brings the past into the presence of the future. The unique act of the past is qualified by the future for the individual human being in the Church which is “Christ existing as Church”. Christ is the subject of the congregation and of the proclamation. God, therefore, reveals God’s self in the Church as a person, as “Christ existing as Church”. The Church is created and founded in Christ. In her, Christ as the new humanity reveals himself. The freedom of God has bound itself to the personally understood Church. The freedom of God is to be free for a human being. The Church therefore truly has the word of forgiveness. The Christian Church can speak forgiveness in word and sacrament. Every member of the Church can also proclaim to the other the gospel and thus “become a Christ” (Bonhoeffer 1988, pp. 107–9).

Because the revelation takes place in the Church, a specifically Christian sociology is required. Bonhoeffer underlines that the unfolding of “reality” presupposes the understanding of the communal dimension and that in reality, the human being is never only an individual. He or she is always in a community: either in “Adam” or in “Christ”. The Word of God is given to humanity, but the gospel is given to the Church of Christ. The revelation is neither only a historical act nor an actualistic and unobjectifiable act without any endurance. In Bonhoeffer’s understanding the being of the revelation “is” the being of a community of Persons which is constituted and closed by the Person of Christ. Thus, (1) the being of the revelation can be thought to be in continuity, (2) the existence of the human being is encountered, and (3) the being of the revelation is not existent, objectifiable, or non-existent, but unobjectifiable (Bonhoeffer 1988, p. 110).

The continuity entails the transsubjective presence of the community of the Church as a personally understood communion, the Church of Christ present here on earth. Because Christ is both the basis of the community and of the faith of the individual believer, the dialectic of act and being is at the same time a dialectic between the individual and community. The revelation is present in the Church in the dialectic between person and community. The Church’s word is homily and sacrament, and her action is faith and love. The basis is that God is a personal relation and being is God’s personal being. Only in the Church can the existence-related being of the revelation be understood (Bonhoeffer 1988, pp. 110–12). Bonhoeffer’s theological ontology is therefore philosophically to be understood as an existential social ontology.

Bonhoeffer thus argues on the basis of the unity of act and being, grounded in the personal presence of Christ as the revelation of the triune God in the Church as the “existent being itself” (seiendes Sein selbst). “Being in the Church” and “being in Christ” are the preconditions of faith, while faith is the precondition for knowing being in the Church as a transsubjective community. The proclamation in word and sacrament creates the Church in the Church by the Church as Christ present. Communio sanctorum and congregatio sanctorum are mutually intertwined, as are word, sacraments, and holy persons. The dialectic of person and community is also a dialectic of Christology and pneumatology. The Holy Spirit as the Spirit of the Father and the Son brings salvific faith to the human being in the Church through the Church as a community of persons and the body of Christ. This implies that the believer participates in the life of the triune God. Both Christ’s work and the Person of Christ, and with him the Father and the Holy Spirit, are present in the believer (Cf. Bonhoeffer 1994, p. 303. For the idea of the presence of Christ in faith in Luther’s theology see the paradigmatic work of Mannermaa 2005).

5. Analogia Trinitatis and Trinitarian Ontology in Ecumenical Ecclesiology

Klaus Hemmerle (1976) has reinterpreted the understanding of the concept analogia entis and suggested that analogia trinitatis might be a more appropriate formulation. Bonhoeffer also criticised analogia entis as a basic category of theological ontology. Ultimately, God existed not only immanently in himself but economically in the Trinity. In Christ, God witnessed his “being for the human being”. Bonhoeffer characterised this analogy between God witnessed by Christ and a Christian as a member of the body of Christ as analogia relationis (Bonhoeffer 1989, pp. 60–61). This is a key term in his trinitarian ontology (Cf. Abromeit 1991, pp. 64–101; Hennecke 1997, p. 246; Wittschier 1987. For Luther’s trinitarian ontology see Mannermaa 1994, pp. 43–60 and Peura 1994, pp. 131–46). It implies the idea of mutual indwelling in the form of an existential social ontology: “being in the Church” and “being in Christ” as the basis of the union with Christ and of the participation in the being of Christ for others. It might be suggested that Bonhoeffer might also have agreed to use the term analogia trinitatis, which expresses a similar intention to that of his term analogia relationis.

Bonhoeffer emphasised the concept of love, caritas, as the bond of unity in the Church as the great idea of Augustine that should not be forgotten. The concept of love also allowed Augustine to formulate creaturely analogies with the Trinity. Communion and love as key terms allowed the expression of the participation in the triune God in the communion of love, and in the indwelling of the Trinity in the Church and in the faithful, as the basis of their unity in love. The same can be said of Luther and Bonhoeffer (Cf. Bonhoeffer 1994, p. 303).

Gregory of Nyssa (c. 335–c. 394) places the apophatic dimension within the core of theological knowledge, which means that the basis of gnoseology is a filial communion, a relation between free persons, and that a human being can approach God knowingly only in love. Similar basic features may also be discerned in Bonhoeffer’s thought. He stresses the dimension of faith more than Gregory, but he also underlines the interconnectedness of faith and love. The apophatic and relational character of his theology becomes explicit, for example, in his article Concerning the Christian Idea of God (1932):

“The basis of all theology is the fact of faith. Only in the act of faith as a direct act is God recognised as the reality which is beyond and outside of our thinking, or our whole existence. Theology, then, is the attempt to set forth what is already possessed in the act of faith. … It knows of its own insufficiency and its limitations. So it must be its highest concern to guard these limitations and to leave room for the reality of God, which can never be conceived by theological thinking. … Personality is free and does not enter the general laws of my thinking. God as the absolutely free personality is, therefore, absolutely transcendent. … [God] reveals himself in absolute self-revelation to man. … [I]dealistic philosophy does not take seriously the ontological category in history. … [I]deas … cannot lead me into the situation of personal decision. … The word of God spoken to me in the act of my faith in Christ is God in his revelation as the Holy Spirit. … [E]ven the answer of man can never be more than ‘I believe, help thou mine unbelief’” (Bonhoeffer 1991, pp. 425–31).

Applying Mannermaa’s finding concerning Luther’s theological ontological theory of knowledge, it can be said that God is sacramentally present in God’s Word for the recipient. God unites himself with the believer through the Holy Spirit in Christ. Christ is thus present in faith, and the triune God is the objective of faith. God as the objective of salvation is the essence itself (ipsa essentia) of the saved. Without this, the saved would be nothing. A relationship with God is the basis of being in God. In conclusion, the relational and the ontological aspects belong together and are in each other. This resembles Bonhoeffer’s understanding that the knowledge of the presence of Christ in the Church for the congregation as the revelation of the triune God is based on a being-already-known (einem Erkanntsein gründet und aufgehoben wird). The reality of the revelation is “being which constitutes the being (the existence) of human beings” (seiendes Sein selbst). The being is “the triune divine Person”, Christ himself, who exists as the church community.

Mannermaa explicitly refers to the importance of the concept of koinonia or communion ecclesiology for ecumenical theology. The explication of the presence of God in the Christian also unfolds the ecclesiological dimension of participation in the triune God. This is the key to an ecumenical communion ecclesiology. The Lutheran input to this discussion makes it important to note that not only Luther and Bonhoeffer teach the real presence of the Holy Trinity in the believer, but the Formula Concordiae does too. Lutheranism thus uses the potential already present in St Augustine’s trinitarian ontology to understand the Church as a communion and as a participation in the life and mission of the triune God (cf. Mannermaa 1994, p. 42).

It seems the analysis supports the thesis of the ecumenical relevance of the Augustinian heritage for the current ecumenical discussion about Trinity and communion ecclesiology. All these contributions (Gregory of Nyssa, Augustine, Luther, Bonhoeffer) pay attention to the constructive dialectic between person and community in a Trinitarian framework (Cf. Lenehan 2018, p. 199). In this way, neither the individual nor the community are neglected but rather combined in the understanding of freedom as a participation in the love of God. From a trinitarian perspective, it is possible to recognise the three Persons in the unity of divine action as separate Persons in a reciprocal relationship with the Others. This has also communion ecclesiological consequences. There is thus no need to be a juxtaposition in the understanding of the theological relevance of the concept of person in the East and West. The conclusion would thus be that these theological contributions have a convergent approach which can be described as a trinitarian ontology. It seems to have a lot to contribute also to the current theological discussion.