Ecumenical Councils of the Orthodox Church

The "Great" or "Ecumenical" Councils, accepted by both East and West, and adopted by a large part of Christendom inasmuch as they defined and defended the fundamental doctrines of the Christian Church, were held either in or near the city of Constantinople.

I. Nicaea 325 Main Teaching: formulated the first part of the Symbol of Faith, known as the "Nicaean Creed," defining the divinity of the Son of God
II. Constantinople 381

Main Teaching: formulated the second part of the Symbol of Faith, defining the divinity of the Holy Spirit. The "Nicaean-Constantinopolitan Creed" remains unchanged in the Orthodox Church since the fourth century. It is recited at every baptism and repeated during each Divine Liturgy

III. Ephesus 431 Main Teaching: proclaimed Jesus Christ as the Incarnate Word of God and Mary as the Theotokos
IV. Chalcedon 451 Main Teaching: proclaimed Jesus Christ as fully divine and fully human, two natures in one person
V. Constantinople 553 Main Teaching: confirmed the doctrines of the Holy Trinity and the person of Jesus Christ
VI. Constantinople 680–681 Main Teaching: affirmed the full humanity of Jesus Christ by insisting on the reality of His human will
Penthekti (or Quinisext) 692 Main Teaching: completed the doctrinal teaching of the fifth and sixth Ecumenical Councils
VII. Nicaea 787 Main Teaching: affirmed the use of icons as genuine expressions of the Christian faith in the doctrine of the divine Incarnation