The Second Ecumenical Council: Constantinople I (AD 381)

• The Second Ecumenical Council was held in AD 381 in Constantinople, the new imperial capital of the Eastern Roman Empire
• It was convened by Emperor Theodosius I, a strong supporter of Nicene Christianity
• The Council of Constantinople in 381 stands as a definitive moment in Christian history.
• Recognized as the Second Ecumenical Council, it provided the theological closure to decades of doctrinal unrest and legally solidified the religious landscape of the Roman Empire.
• By finalizing the Trinitarian synthesis, the council ensured that the "blueprints" drawn at Nicaea were fully realized into a robust theological fortress.
• Unlike Nicaea, this council was initially Eastern in composition and later recognized as ecumenical by the whole Church
• About 150 bishops attended, almost entirely from the Eastern Church
• The council was called because the Nicene faith was still under serious threat
• After Nicaea, Arianism did not disappear but evolved into new forms
• Many bishops accepted semi-Arian formulas that weakened Nicene teaching
• Political pressure repeatedly favoured Arian or semi-Arian parties

Historical Context and the Imperial Mandate

• The path to Constantinople was paved by political and ecclesiastical shifts.
• A key historical background was the long conflict between Nicene bishops and Arian-leaning emperors
• Emperor Constantius II favoured Arian theology and persecuted Nicene bishops
• St Athanasius of Alexandria was exiled multiple times for defending Nicene faith
• The Church experienced deep division and instability
• Following the death of the Arian Emperor Valens at the Battle of Adrianople in 378, Emperor Theodosius I took control of the East with a mission to restore Nicene Christianity. [i]
• In 380, Theodosius issued the Edict of Thessalonica, a landmark decree that mandated all subjects follow the faith held by the bishops of Rome and Alexandria, effectively outlawing Arianism. [ii]
• To provide a formal theological anchor for this edict, Theodosius convened approximately 150 orthodox bishops in the capital city in May 381. [iii]
• Notably, this was primarily an Eastern assembly; the Western church and the Bishop of Rome were not represented, yet its decisions would eventually achieve universal acceptance.
• A temporary pagan revival under Emperor Julian the Apostate (361–363) attempted to weaken Christianity
• Julian allowed exiled bishops to return, hoping Christian divisions would destroy the Church from within
• Instead, Nicene theology became more clearly defined
• New theological disputes emerged concerning the Holy Spirit
• Some groups accepted the divinity of the Son but denied the divinity of the Holy Spirit
• These groups were later called Pneumatomachians, meaning “fighters against the Spirit”
• The key theological question was whether the Holy Spirit is truly God
• Scripture speaks clearly of the Spirit acting as God, giving life, sanctifying, and being worshipped
• “The Lord is the Spirit” (2 Corinthians 3:17 NIV)
• “You have not lied just to human beings but to God” (Acts 5:4 NIV), spoken about the Holy Spirit

The Neo-Nicene Synthesis and the Role of the Cappadocian Fathers

• St Basil the Great played a crucial role before the council
• He defended the divinity of the Holy Spirit using careful biblical and liturgical language
• He showed that the Spirit receives the same worship and honour as the Father and the Son
• His work prepared the theological ground for the council
• The Cappadocian Fathers—Basil the Great, Gregory of Nyssa, and Gregory of Nazianzus—were central figures
• The council’s intellectual backbone was the work of the Cappadocian Fathers: Basil the Great, Gregory of Nazianzus, and Gregory of Nyssa. [iv]
• They clarified the distinction between one divine essence and three divine persons
• This balanced unity and distinction without division or confusion
• They resolved the linguistic "fog" that had obscured the Church’s message since 325 by refining Greek terminology to describe the nature of God: [v]
  • Ousia (Essence): Refers to the single, shared divine nature.
  • Hypostasis (Person): Refers to the three distinct individuals—Father, Son, and Holy Spirit—within that nature.
• This formula of "three hypostases in one ousia" allowed the Church to affirm that God is one while remaining truly distinct in three persons.
• Gregory of Nazianzus briefly presided over the council as Bishop of Constantinople
• He strongly defended Nicene orthodoxy and the divinity of the Holy Spirit
• He later resigned due to political opposition and ecclesiastical tensions

The Niceno-Constantinopolitan Creed

• The council reaffirmed the faith of Nicaea without changing its core teaching
• While the Council of Nicaea (325) provided the foundation, Constantinople produced the expanded version of the Creed used by most Christians today.
• The council reaffirmed that the Son is homoousios ("of the same essence") with the Father but added crucial clauses to refute contemporary heresies:
  1. Christ’s Humanity: Explicitly mentioned His birth of the Virgin Mary and His crucifixion under Pontius Pilate.
  2. The Holy Spirit: To combat the Pneumatomachians (those who denied the Spirit’s deity), the Creed defined the Spirit as "the Lord and the Life-giver" who "proceeds from the Father" and is "worshipped and glorified together" with the Father and the Son. [vi]
• It clarified the article on the Holy Spirit
• The Spirit is confessed as “the Lord, the giver of life”
• He “proceeds from the Father”
• He is worshipped and glorified together with the Father and the Son
• This creed clearly affirmed the full divinity and personhood of the Holy Spirit
• The Spirit is not a creature or force but true God
• The Spirit speaks through the prophets and sanctifies the Church
• “Go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit” (Matthew 28:19 NIV)
• This baptismal formula underlines equality and unity within the Trinity

Condemnation of Heresies

• The council did not merely build up doctrine; it actively tore down opposing views through formal anathemas: [vii]
• It rejected all forms of Arianism and semi-Arianism
• It condemned Macedonianism, which denied the divinity of the Holy Spirit
• Arianism: All variants, including strict Anomoeans and moderate Homoeans, were condemned.
• Apollinarianism: This view suggested the divine Logos replaced Jesus' human mind. The council rejected this, asserting Christ had a rational human soul. [35, 36] As Gregory of Nazianzus famously argued: "What has not been assumed has not been healed."
• Sabellianism: The idea that God is one person wearing different "masks" or modes was firmly repudiated.

Political and Ecclesiastical Reorganization

• The council also addressed ecclesiastical order
• The council also reshaped church power structures.
• After Gregory of Nazianzus resigned as Bishop of Constantinople due to procedural disputes, Nectarius was appointed to the see. [44, 45]
• It recognized the Bishop of Constantinople as holding honor second only to Rome
• This was based on Constantinople being the “New Rome”
• Most controversially, Canon 3 decreed that the Bishop of Constantinople should hold the "primacy of honor" immediately after the Bishop of Rome, because Constantinople was "New Rome."
• While the Emperor viewed this as a logical political alignment, the Roman see rejected the canon, arguing that ecclesiastical priority should be based on apostolic succession rather than imperial politics.
• This canon later became a point of tension between East and West

Conclusion: Completion of Trinitarian Orthodoxy

• From an Orthodox Coptic perspective, doctrine was defined without dependence on imperial power
• Although emperors convened councils, truth was determined by apostolic faith
• The Holy Spirit guided the bishops in continuity with Scripture and tradition
• The council completed the Trinitarian framework begun at Nicaea
• Father, Son, and Holy Spirit are one God, equal in divinity, distinct in person
• This protected Christian worship, prayer, and salvation
• The council’s teaching safeguards salvation
• Only if the Spirit is God can He truly sanctify and unite believers to God
• “He saved us through the washing of rebirth and renewal by the Holy Spirit” (Titus 3:5 NIV)
• The Council of Constantinople brought a definitive close to the "Nicene Struggle."
• It was an era likened to a ship surviving a fifty-year storm before finally docking in harbor.
• By shoring up the deity of the Holy Spirit and the full humanity of Christ, the 381 assembly ensured the theological structure of Christianity could withstand the battering rams of heresy for centuries to come.
• Constantinople I became foundational for all later Orthodox theology
• It is accepted by the Coptic Orthodox Church without reservation
• Its creed remains central in the Church’s liturgy
• The council confirmed that doctrinal truth develops in clarity, not in contradiction
• The Church does not invent doctrine but defends revealed truth
• “The Spirit of truth…will guide you into all the truth” (John 16:13 NIV)
• Constantinople I stands as the council that completed the Church’s confession of the Holy Trinity
• It preserved the faith once delivered to the saints
• It strengthened the Church against heresy and confusion

[i] Needham, Nick. 2,000 Years of Christ's Power, Vol. 1: The Age of the Early Church Fathers. Grace Publications Trust / Christian Focus Publications, 2016 (revised edition). Chapter 7, Section 3.

[ii]  Shelley, Bruce L. Church History in Plain Language. Various editions (e.g., 5th ed., updated by Marshall Shelley, Zondervan, 2021; or 4th ed., Thomas Nelson, 2013). Chapter 9.

[iii]  كيرلُّس الأنطوني (القمص). عصر المجامع [The Age of the Councils]. مكتبة المحبة [Library of Love Publications]. (Arabic book on the ecumenical councils,

[iv]  Needham, Nick. 2,000 Years of Christ's Power, Vol. 1: The Age of the Early Church Fathers. Grace Publications Trust / Christian Focus Publications, 2016 (revised edition). Chapter 8, Section 3.

[v]  Ferguson, Everett. Church History, Volume One: From Christ to the Pre-Reformation: The Rise and Growth of the Church in Its Cultural, Intellectual, and Political Context. Zondervan, 2005/2013. Chapter 11, Section I-

           [vi] Ferguson, Everett. Church History, Volume One. Chapter 11

[vii] IBID