The First Ecumenical Council: A Pillar of Orthodox Faith and Unity

When Orthodox Christians chant the Creed during the Divine Liturgy, “I believe in one God, the Father Almighty…”, they are proclaiming the fruit of the First Ecumenical Council, held in Nicaea in AD 325. This seminal event, convened under the auspices of Emperor Constantine the Great, marks a foundational moment in the life of the Church, one that still shapes the theology, liturgical life, and ecclesial identity of the Orthodox Christian world.

Historical Context: The Rise of Heresy and the Need for Unity
By the early fourth century, Christianity had emerged from the catacombs into the public square. The Edict of Milan in 313 had ended the persecution of Christians in the Roman Empire, and the Church, once marginalized, now faced new internal challenges. Chief among them was the rise of the Arian controversy.

Arius, a presbyter in Alexandria, taught that the Son of God was not co-eternal with the Father, asserting instead that “there was a time when He was not.” This teaching struck at the heart of the Christian understanding of Christ’s divinity and undermined the very possibility of salvation, for if Christ were not fully God, He could not deify humanity.

To address this grave theological division and preserve the unity of the Church, Emperor Constantine called together bishops from throughout the Christian world to the city of Nicaea (modern-day İznik, Turkey). Around 318 bishops, primarily from the Eastern provinces of the Empire, gathered in what would become known as the First Ecumenical Council.

The Creed of Nicaea: Defending the Divinity of Christ
​The most significant outcome of the Council was the formulation of the original Nicene Creed, which was later expanded at the Second Ecumenical Council (Constantinople, 381) to include statements on the Holy Spirit and the Church. The central theological affirmation was that the Son is homoousios, of the same essence, with the Father.

This term, homoousios, was not a scriptural word, but the Church Fathers at Nicaea, especially St. Athanasius, who would become the chief defender of Nicene Orthodoxy, understood that the mystery of the Incarnation could not be preserved if Christ were anything less than fully divine. By affirming the Son's consubstantiality with the Father, the Church safeguarded the doctrine of the Holy Trinity and laid the groundwork for the full articulation of Orthodox Christology.

Canonical Decisions: Ecclesial Structure and DisciplineIn addition to the Creed, the Council of Nicaea issued twenty canons addressing ecclesiastical order and discipline. These canons provided guidance on a variety of issues such as the reconciliation of lapsed Christians, the jurisdiction of bishops, and liturgical norms. Notably, Canon 6 affirmed the primacy of the bishops of Rome, Alexandria, and Antioch within their respective regions, setting a precedent for the structure of the Church’s hierarchy.

The conciliar model, bishops gathered in synod to discern the truth guided by the Holy Spirit, became the hallmark of Orthodox ecclesiology. While the Bishop of Rome would later assert universal jurisdiction in the West, the East maintained a conciliar model rooted in the consensus of the bishops, a principle upheld to this day.

The Lasting Impact on the Eastern Orthodox Church
The First Ecumenical Council remains a cornerstone of Orthodox Christian identity. Its theological definitions are not merely historical footnotes but living realities in the life of the Church. Orthodox Christians affirm the Nicene-Constantinopolitan Creed (without the later Western addition of the filioque) at every Divine Liturgy, and the council's emphasis on conciliarity continues to shape the governance of the Orthodox Church.
1. Theological Clarity and Doctrinal Unity
The Council’s clear rejection of Arianism preserved the Orthodox understanding of salvation as theosis, the process of becoming by grace what God is by nature. Only if Christ is fully God can He unite humanity to God. This doctrine remains at the heart of Orthodox soteriology and spirituality.
2. Liturgical Continuity
The Creed born at Nicaea is not merely recited, it is sung, chanted, and internalized. It serves as both a theological confession and a liturgical proclamation. In an age of doctrinal relativism, this unchanging Creed is a signpost of Orthodox continuity with the early Church.
3. Conciliarity over Papal Supremacy
The model of church governance embodied by Nicaea, rooted in synodality and consensus, stands in contrast to centralized ecclesiastical models. For the Orthodox, the truth is discerned through the gathered body of bishops, not through unilateral authority. This has profound implications for how the Orthodox Church addresses contemporary challenges, such as questions of autocephaly, liturgical uniformity, and ecumenical dialogue.
4. A Warning Against Heresy
The enduring relevance of the First Ecumenical Council also lies in its warning against the dangers of theological innovation. Arius was not a fringe figure but a respected cleric. His error illustrates how subtle deviations from apostolic doctrine can have far-reaching consequences. The Orthodox Church, faithful to the spirit of Nicaea, continues to guard against modern-day equivalents of Arianism, ideologies that diminish Christ’s divinity or reduce the mystery of salvation to moralism or activism.

Nicaea Today: Living the Legacy
In today’s world, where truth is often seen as subjective and theological boundaries are blurred, the decisions of the First Ecumenical Council serve as an anchor. Orthodox Christians, whether living in the urban centers of Eastern Europe or in the deserts of Arizona, are part of a living tradition that proclaims the same faith once delivered to the saints.

For converts to Orthodoxy, the Creed is often the first liturgical proclamation they memorize. For cradle Orthodox, it is a lifelong catechesis. For all, it is a declaration that the faith we confess today is the faith of Nicaea, the faith of the Apostles, the faith of the Fathers.

Conclusion: “As it was in the beginning…”
The First Ecumenical Council was not a theological debating society, it was the Holy Spirit working through the Church to clarify and defend the mystery of the Incarnation. Its decisions continue to affect every Orthodox Christian, whether in belief, in worship, or in the structure of the Church.

In an age of division, the unity forged at Nicaea offers a vision of communion rooted not in compromise, but in truth. And for Orthodox Christians today, the legacy of Nicaea is not merely a historical memory, it is a living inheritance.

“Glory to Thee, O Christ our God, the Apostles’ boast, the Martyrs’ joy, whose preaching was the consubstantial Trinity!”