TRIUNE GOD AND THE IDENTITY OF THE CHURCH
Keynote presentation at the VI World Conference on Faith and Church Order at the Logos Papal Centre of the Coptic Orthodox Church
Wadi Natrun, Egypt, 25 October 2025
The World Council of Churches defines itself as “a fellowship of churches which confess the Lord Jesus Christ as God and Saviour according to the Holy Scriptures, and which therefore seek to fulfil their shared vocation for the glory of God the Father, Son, and Holy Spirit.” With this basic statement, the World Council of Churches expresses its ecclesial identity of faith in its “Constitution and Rules” from 2022. By professing Jesus Christ as “God and Saviour” and allowing this profession to flow into the Trinitarian doxology, it makes it unmistakably clear that it stands on the ground of the Council of Nicaea.
Gift of a common Christian creed
This is self-evident today, but it has not always been the case throughout history. At the beginning of the fourth century, a fierce dispute broke out above all in the eastern part of the Roman Empire, highlighting that the fundamental question of who Jesus Christ is had become the “problem of Christian monotheism.”[1] The theological debate has primarily focused on how Christian belief in Jesus Christ as the Son of God can be harmoniously reconciled with the equally Christian belief in the one God in terms of the monotheistic confession.
The dispute was primarily provoked by the Alexandrian presbyter Arius, who advocated strict monotheism in line with the philosophical thinking of the time. To maintain this position, he excluded Jesus Christ from the concept of God. In his conviction that there can only be one God, Jesus Christ cannot be the ‘Son of God’ in the true sense, but only an intermediary being whom God uses in the creation of the world and in his relations with human beings. This does not mean, of course, that Jesus Christ is simply a creature like the others: rather, he is ontologically distinguished as a creature before all creation. The Son is indeed created by God, but not like the other creatures. However, because of the strong emphasis on the transcendence and unity of God, Jesus Christ cannot, in Arius’ view, be eternal in the same way as God; only the one God can be uncreated and eternal.[2]
Since this serious doctrinal problem could not be resolved at the local synods of the Church in Alexandria, Emperor Constantine summoned all bishops to a pan-church synod in the city of Nicaea in Asia Minor. In the “Letter of the Synod of Nicaea to the Egyptians”, the bishops announced after lengthy deliberations that they had unanimously decided to anathematise Arius’ “hostile attitude towards the faith” and “his blasphemous statements and designations, with which he reviled the Son of God.” The bishops thus rejected the model of strict philosophical monotheism propagated by Arius with the creed that the one Lord Jesus Christ is the Son of God: “born of the Father as the only begotten, that is, of the substance of the Father, God from God, light from light, true God from true God, born, not created, of one substance with the Father, through whom all things were made in heaven and on earth.”
While the Council of Nicaea defined belief in Jesus Christ, it only mentioned belief in the Holy Spirit in general terms. “and in the Holy Spirit”. It was not until the Council of Constantinople that the creed concerning the Holy Spirit was defined in detail. This enabled the formulation of the dogma of the Holy Trinity, which is specific to Christian monotheism. The Nicene Creed therefore marks an important, albeit incomplete, step towards the Great Creed of Constantinople in 381.
The confession of Christ as interpretation of the communication between the Son and the Father
The decisive term in the Nicene Creed is the Greek word “homoousios”. This raises the question of whether the Council Fathers did not thereby “Hellenise” the biblical faith and burden it with a foreign philosophy, as the Council of Nicaea has been repeatedly accused of doing by many theologians since the Protestant church historian Adolf von Harnack in the 19th century. According to Harnack, not the Son but only the Father belongs in the Gospel as proclaimed by Jesus, [3] which is why Christological dogma would have replaced the Gospel of Jesus with a construct of Greek philosophy.
However, when we compare the Christological confession of Nicaea with the confession of Christ as presented in the New Testament, we find more similarities than differences. In the New Testament, Jesus is most clearly seen as the Son of the heavenly Father in his prayers. So the innermost core of the historical figure of Jesus of Nazareth is encountered in the predication of Jesus as the Son. If the essence of the biblical view of Jesus is his constant prayerful communication with his Father, then it is reasonable to conclude that the innermost mystery of Jesus, as revealed in Scripture — that he is the faithful Son of the Father — was accurately expressed at the Council of Nicaea with the term “homoousios”. With this statement, the Council provided an adequate interpretation of Jesus’ prayer, as Joseph Ratzinger rightly observed: “The core of the dogma defined in the early Church councils is the assertion that Jesus is the true Son of God, of the same substance as the Father, and through the Incarnation, of the same substance as us. Ultimately, this definition is an interpretation of the life and death of Jesus, which was always destined to be the conversation between the Son and the Father.”[4]
The Council of Nicaea did not “Hellenise” the Christian faith with the word “homoousios”; rather, it expressed the incomparable newness and uniqueness that is visible in the relationship between the Son and the Father as attested to in the Bible. Regarding Christological dogma, it is therefore more accurate to speak of “a Christianisation of Greek thought than a Hellenisation of the Gospel”.[5] While the Council of Nicaea used contemporary philosophy to articulate the distinguishing features of the Christian faith, it was in fact the Alexandrian presbyter Arius who adapted the Christian faith to the enlightened Greek thinking of the time, thereby transforming it.
Christian transformation in the concept of God
This conclusion is particularly evident when we consider the transformation in the concept of God that took place at the Council of Nicaea in 325 and was completed at the Council of Constantinople in 381, and which becomes clear when compared with the Greek concept of God. This is characterised by the assumption of a strict and, as it were, unity without relations, which is why multiplicity represents an inferior reality. From a religious point of view, ancient thinking considers only unity to be divine, whereas multiplicity arises from decay and tends towards it, and therefore appears as the decay of unity.
By contrast, the Council of Nicaea’s definition of the consubstantiality of the Son with the Father, and the subsequent exposition of the mystery of God’s one substance in three divine persons, opens up space for multiplicity in the concept of God itself. Consequently, unity and multiplicity are both reflection and participation in the divine: “Not only is unity divine, but multiplicity is also an original concept with an inner reason in God himself.”[6] Unity and multiplicity thus lie ontologically on the same level, with the consequence that the God revealed in Christianity is precisely one in the multiplicity of relationships between the divine persons.
Another closely related fact is that the Trinitarian concept of God has broken down the sole dominance of substance thinking. Instead, relation is now regarded as an equally essential mode of reality as substance. Consequently, God is no longer to be considered a monadic unity, but rather as unity in relation. The relationship between the eternal Son and the eternal Father also shows that not only relationships exist in God but also that God himself is “a being of relationship.”[7]
Thus, the Christian transformation in the concept of God consists of the harmonious coexistence of unity and multiplicity in God. On the one hand, the Trinitarian mystery of God contains the beautiful message that there is room for the other in God himself: The Father is different from the Son, and the Son is different from the Holy Spirit. There is an original and beautiful diversity of persons living in the divine Trinity. Accordingly, the Church has condemned modalism as heretical, since this doctrine asserts that the one divine being merely manifests itself in three different ways. However, the Church professes that God is also different in the distinctness of persons within himself.
On the other hand, the diversity of the divine persons in the Trinity precludes an unconnected pluralism. Although the Father, the Son and the Holy Spirit are distinct from one another, the divine persons live as heavenly trialogue partners on the same level of being: The Father is God, the Son is God, and the Holy Spirit is God. There is an original and wonderful unity of persons in God or, as the Orthodox theologian Paul Evdokimov says, a “pre-eternal Trinitarian council.”[8] The Church has therefore condemned tritheism, which misunderstands the Trinity as a federalist community of gods, as heresy. For the Church professes that God is in himself a living community in the original relational unity of love.
The church as icon of the Trinity
This combination of unity and multiplicity in God has consequences for the theological description of the Church’s identity. The Church knows that it is called upon to live in the world as a credible icon of the Triune God. In this sense, Faith and Order is also convinced, in its study on “The Church”, that the “characteristic of synodality or conciliarity” reflects the “mystery of the Trinitarian life of God” [9], insofar as God reveals himself in his innermost life as “syn” – “with” – as Father, Son and Holy Spirit.
In Catholic ecclesiology, the Church as icon of the Trinity is understood as a communion in the unity of the universal Church and the multiplicity of local churches constituted by bishops. Just as the unity of God can be recognised in the Trinity of Persons, so too can the unity of the universal Church be recognised and realised in the multiplicity of local churches. And just as in the Trinity the triunity of persons neither negates nor produces the unity of the divine substance, so too the one universal Church is something qualitatively different from a mere federation of independent individual churches, even though it consists of and is made up of local churches. In this sense, the Catholic Church understands itself as both communio ecclesiae and communio ecclesiarum.
The Second Vatican Council recalled this ecclesiological intertwining of the plural “churches” with the singular “church”. This intertwining encompasses the ecumenical problem as a whole; in this context, the plural “churches” refers to churches and communities not yet in full communion with the Catholic Church. The ecumenical problem lies in the fact that the Catholic model of the unity of the universal Church and the multiplicity of local churches cannot simply be transferred and applied to those churches and communities that have come into being through divisions, since divisions are fundamentally alien to the innermost nature of God.
In order to make further progress towards the hoped unity, two models must be ruled out. The first is the model of so-called return ecumenism, which would involve all non-Catholic churches and ecclesial communities returning to the bosom of the Catholic Church. This model would confuse the search for unity with uniformity and absolutise it, thus representing ecclesiological modalism in ecumenism.
However, the model described by Cardinal Walter Kasper as “federation ecumenism” must also be ruled out.[10] According to this model, all churches that are still separated would recognise each other as churches and join together in unity on the basis of the one baptism while preserving their current status quo. However, this model, which is favoured above all in the Protestant world, is not conceivable as a solution to the ecumenical problem from a Catholic or Orthodox perspective, because its absolutisation of diversity represents an ecclesiological tritheism. If more or less everything were to remain status quo in the churches that are still separate, it would be difficult to speak of Church unity.
Nicaea as a milestone in ecumenical unity
The insight that these two paths do not lead to the future was already recognised by the French philosopher Blaise Pascal, emphasising that unity that does not depend on multiplicity is dictatorship, and that multiplicity that does not depend on unity is anarchy. In the ecumenical movement, too, we must constantly seek a middle way between dictatorship and anarchy. And this means that the ecumenical movement is called and obliged to reconsider the fundamental relationship between unity and multiplicity in a fundamental way, namely in the light of the Trinitarian mystery, in order to gain an ecumenical identity for the Church in this way.
In this sense, I see the 1700th anniversary of the Council of Nicaea as a particular challenge and opportunity. It reminds us that ecumenism is fundamentally a matter of faith, and that the unity of the Church cannot be rediscovered without the truth of faith. This is because its restoration requires agreement on the essential content of the faith, not only among today’s churches and ecclesial communities, but also with the Church of the past and, above all, its apostolic origins. The unity of the Church can never be anything other than unity in the apostolic faith – the faith handed down and entrusted to every new member of the body of Christ at baptism.
The Council of Nicaea is of particular ecumenical significance because it took place at a time when Christianity had not yet been wounded by the numerous divisions that followed. Its creed is therefore common to all Christian churches and ecclesial communities, uniting them to this day. As the Protestant ecumenist Wolfhart Pannenberg has emphasised, it is “associated with a claim to universal ecclesial validity and was also received by the early Church as binding on all Christians.”[11] Its ecumenical significance cannot therefore be underestimated.
For this reason, it is to be hoped and desired that the 1700th anniversary of the Council of Nicaea will be celebrated by all of Christianity in an ecumenical spirit, and that the creed will be reappropriated in ecumenical fellowship. This will allow further steps to be taken towards restoring the unity of the Church. This conference in Egypt, organised by Faith and Order, has a particular responsibility to reconsider questions of faith and church structures. If our shared reflection on the mystery of the Triune God sheds new light on the identity of the Church, the 1700th anniversary of the Council of Nicaea could become a milestone in ecumenical unity.
[1] J. Kardinal Ratzinger, Das Credo von Nikaia und Konstantinopel. Geschichte, Struktur und Gehalt, in: Ders., Theologische Prinzipienlehre. Bausteine der Fundamentaltheologie (München 1982) 116-127, zit.123.
[2] Vgl. Th. Böhm, Die Theologie des Arius, in: U. Heil und J.-H. Tück (Hrsg.), Nizäa – das erste Konzil. Historische, theologische und ökumenische Perspektiven (Freiburg i. Br. 2025) 111-126.
[3] A. von Harnack, Das Wesen des Christentums, hrsg. von Trutz Rendtorff (Gütersloh 1999) 154.
[4] J. Kardinal Ratzinger, Christologische Orientierungspunkte, in: Ders., Schauen auf den Durchbohrten. Versuche zu einer spirituellen Christologie (Einsiedeln 1984) 13-40, zit. 29.
[5] K.-H. Menke, Das Homoousios to Patri scheidet die Geister. Zur kriteriellen Funktion des Symbolum Nicaenum, in: U. Heil und J.-H. Tück (Hrsg.), Nizäa – das erste Konzil. Historische, theologische und ökumenische Perspektiven (Freiburg i. Br. 2025) 364-384, zit. 365.
[6] J. Ratzinger, Einführung in das Christentum. Vorlesungen über das Apostolische Glaubensbekenntnis (München 1968) 139-140.
[7] J.-H. Tück, Die Homoousie eine „Revolution“ im Gottesbegriff? Das nizänische Bekenntnis als Weichenstellung, in: U. Heil und J.-H. Tück (Hrsg.), Nizäa – das erste Konzil. Historische, theologische und ökumenische Perspektiven (Freiburg i. Br. 2025) 423-462, zit. 442.
[8] P. Evdokimov, Welches sind die Hauptanliegen der orthodoxen Kirche gegenüber der katholischen Kirche? in: Concilium 2 (1966) 267.
[9] The Church: Towards a common vision. A study by the Faith and Order Commission of the World Council of Churches (WCC) (Geneva 2013), No. 5.3.
[10] W. Kasper, Der Wahrheit auf der Spur. Mein Weg in Kirche und Theologie (Freiburg i. Br. 2025) 142.
[11] W. Pannenberg, Die Bedeutung des Bekenntnisses von Nicaea-Konstantinopel für den ökumenischen Dialog heute, in: Ders., Beiträge zur Systematischen Theologie. Band 3: Kirche und Ökumene (Göttingen 2000) 194-204, zit. 197.