8. The Seven Ecumenical Councils, and Why They Matter

 

The Seven Ecumenical Councils stand as pillars of truth within the life of the Orthodox Church. They are not simply historical gatherings of bishops and theologians, but sacred moments in which the Holy Spirit guided the Church to preserve the purity of the apostolic faith. From the first council at Nicaea in 325 A.D. to the seventh at Nicaea II in 787 A.D., these assemblies defined the essential doctrines of Christianity—clarifying who Christ is, how we worship, and what it means to live in communion with God.

Each council was called to respond to a crisis of belief. Heresies and false teachings arose that threatened to distort the revelation entrusted to the Apostles. Yet, through prayer, debate, and the discernment of the Holy Spirit, the Church proclaimed with authority the truth that “Jesus Christ is the same yesterday, today, and forever” (Hebrews 13:8). The Councils did not invent new doctrines but articulated more clearly what the Church had always believed. In this sense, they are milestones of continuity—defending, not redefining, the Faith.

Why do these Councils matter today? Because every Christian confession, prayer, and liturgical act rests upon the foundations they laid. When we recite the Nicene-Constantinopolitan Creed, we are professing the faith shaped by the first two Councils. When we venerate an icon, we are affirming the truth of the Seventh. When we confess that Christ is one divine Person with two natures, we echo the wisdom of Chalcedon. The Councils remind us that Orthodox theology is not abstract speculation but the living confession of the Church, grounded in worship and experience of the Triune God.

For catechumens and inquirers, studying the Seven Ecumenical Councils opens a window into how the Church has preserved the Gospel across centuries of challenge and change. Each sub-post in this section will explore a specific Council—its historical context, major figures, heresies addressed, and enduring spiritual significance. These were not mere academic debates but life-and-death struggles for the truth of who God is and how He saves.

To know the Councils is to understand the faith of the Church that Christ Himself established. Their decrees still shape every Liturgy, every sacrament, and every confession of faith we make. In reading and reflecting on them, we discover not the distant past, but the living heart of Orthodoxy—unchanged, undivided, and ever alive in the life of the Holy Spirit.

1. The First Ecumenical Council – Nicaea I (325 A.D.)

Key Issue: The divinity of Christ.

Summary: Convened by Emperor Constantine, the First Council of Nicaea confronted the Arian heresy, which claimed that the Son was a created being and not truly divine. The Council declared that the Son is homoousios—of one essence—with the Father. The original Nicene Creed was formulated here, affirming Christ as “true God from true God.” This Council established the foundation for all subsequent Trinitarian theology.

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2. The Second Ecumenical Council – Constantinople I (381 A.D.)

Key Issue: The divinity of the Holy Spirit and completion of the Creed.

Summary: The First Council of Constantinople expanded the Nicene Creed to include a full confession of the Holy Spirit as “the Lord, the Giver of Life, who proceeds from the Father.” It condemned the Pneumatomachians (Macedonians) who denied the Spirit’s divinity and reaffirmed the full equality of the three Persons of the Holy Trinity.

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3. The Third Ecumenical Council – Ephesus (431 A.D.)

Key Issue: The unity of Christ’s person and the title Theotokos.

Summary: This Council, led by St. Cyril of Alexandria, condemned the Nestorian heresy, which separated Christ into two distinct persons—one divine and one human—and refused to call the Virgin Mary Theotokos (“God-bearer”). The Council affirmed that the Word of God truly became man and that Mary rightly bears this title because she gave birth to the one divine Person, Jesus Christ, our Lord.

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4. The Fourth Ecumenical Council – Chalcedon (451 A.D.)

Key Issue: The two natures of Christ.

Summary: The Council of Chalcedon clarified the Church’s teaching on the Incarnation, rejecting both Nestorian division and Eutychian confusion of Christ’s natures. It proclaimed the definition that Christ is one Person in two natures—fully divine and fully human—“without confusion, change, division, or separation.” This balanced formula became the cornerstone of Orthodox Christology.

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5. The Fifth Ecumenical Council – Constantinople II (553 A.D.)

Key Issue: Further Christological clarity and condemnation of heretical writings.

Summary: This Council sought to reconcile disputes after Chalcedon by condemning certain writings (the “Three Chapters”) that seemed to support Nestorian tendencies. It reaffirmed the unity of Christ’s person and the teachings of St. Cyril of Alexandria, preserving the truth that the same divine Person who is the eternal Word suffered in the flesh for our salvation.

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6. The Sixth Ecumenical Council – Constantinople III (680–681 A.D.)

Key Issue: The two wills and two energies of Christ.

Summary: In response to the heresy of Monothelitism, which taught that Christ had only one divine will, this Council affirmed that Christ possesses two natural wills and two energies—divine and human—working in harmony. This teaching safeguarded the fullness of Christ’s humanity and divinity and showed that His human obedience was real, not merely symbolic.

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7. The Seventh Ecumenical Council – Nicaea II (787 A.D.)

Key Issue: The veneration of holy icons.

Summary: The final Ecumenical Council restored the veneration of icons after the period of Iconoclasm, affirming that since the Word of God truly became flesh, matter can be a vehicle of divine grace. The Council distinguished between veneration (honor) given to icons and worship (latreia) due to God alone. Icons are windows to the divine, proclaiming the reality of the Incarnation and the sanctification of creation.