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 |
