On the 1,700th Anniversary of the Council of Nicaea: Opportunity and Challenge for Ecumenism

In the midst of the 2025 Jubilee Year — a Holy Year proclaimed by Pope Francis to rekindle Christian hope — the 1,700th anniversary of the first Ecumenical Council in Church history, held in Nicaea in 325, will also be celebrated. This anniversary has significant ecumenical dimensions, made evident by the fact that the Holy Father has expressed a desire to travel to Nicaea to commemorate the event together with the Ecumenical Patriarch, Bartholomew i. The Faith and Order Commission of the World Council of Churches is also preparing for this celebration.

The Common Profession of the Christian Faith

Of particular ecumenical relevance are the doctrinal issues addressed by the Council, which are summarised in the “Declaration of the 318 Fathers”. With this Declaration, the Fathers professed their faith in:

“one God the Father all powerful, maker of all things both seen and unseen.
And in one Lord Jesus Christ, the Son of God, the only-begotten begotten from the Father, that is from the substance of the Father, God from God, light from light, true God from true God, begotten not made, consubstantial with the Father, through whom all things came to be, both those in heaven and those in earth”.

Historical Context and the Arian Controversy

The historical backdrop is that of a violent dispute which broke out in Christianity at the time, especially in the Eastern part of the Roman Empire. In the early fourth century, the Christological question had become a central issue of Christian monotheism. The controversy mainly revolved around how to reconcile the profession of Christian faith in Jesus Christ as the Son of God with the equally Christian faith in one God, in accordance with the monotheistic confession.

Arius of Alexandria, a theologian, advocated especially for a strict monotheism in line with the philosophical thought of his era and, to maintain such a strict monotheism, he excluded Jesus Christ from the concept of God. From this perspective, Christ could not be “Son of God” in the real sense of the word, but merely an intermediary whom God uses for the creation of the world and for his relationship with human beings.

The Council’s Theological Response

The Council Fathers rejected this model of strict philosophical monotheism that Arius spread, and they set it against the creed according to which Jesus Christ, as Son of God, is “consubstantial with the Father”. With the word, “ homoousios”, the Council Fathers sought to express the deepest mystery of Jesus Christ, which Sacred Scripture testifies to as faithful Son of the Father, to whom he is intimately united in prayer. This is precisely what the Council Fathers of Nicaea sensibly realized, using the term “ homoousios” to offer the correct interpretation of Jesus’ prayer and a deeper interpretation of his life and death, which were marked at every moment by dialogue with the Father.

In the Nicene Creed, the Council again expressed itself as Peter and with Peter at Caesarea Philippi: “You are the Christ, the Son of the living God” ( Mt 16:16). The Council’s Christological creed became the base of the common Christian faith.

Key Doctrinal Differences at Nicaea

Arius of Alexandria: Advocated for a strict monotheism and excluded Jesus Christ from the concept of God, viewing Him as an intermediary.
Council Fathers: Declared Christ as “consubstantial with the Father” (homoousios), rooted in His prayerful dialogue with the Father.
Outcome: The Council used the philosophy of that era to express what was characteristic of the Christian faith rather than conforming it to unrelated philosophy.

Without this prayerful attitude, one cannot understand Jesus Christ. With the word “ homoousios”, the Council of Nicaea did not “Hellenize” biblical faith, submitting it to an unrelated philosophy, but rather, embraced the incomparable newness made visible in Jesus’ prayer to the Father.