As the Church progressed through history it was faced with many difficult decisions. The Church always settled difficulties and made decisions by reaching a consensus of opinion among all the believers inspired by God who were led by their appointed leaders, first the apostles and then the bishops.
The first church council in history was held in the apostolic church to decide the conditions under which the gentiles, that is, the non-Jews, could enter the Christian Church (see Acts 15). From that time on, all through history councils were held on every level of church life to make important decisions. Bishops met regularly with their priests, also called presbyters or elders, and people. It became the practice, and even the law, very early in church history that bishops in given regions should meet in councils held on a regular basis.
At times in church history councils of all of the bishops in the church were called. All the bishops were not able to attend these councils, of course, and not all such councils were automatically approved and accepted by the Church in its Holy Tradition. In the Orthodox Church only seven such councils, some of which were actually quite small in terms of the number of bishops attending, have received the universal approval of the entire Church in all times and places. These councils have been termed the Seven Ecumenical Councils(see table below).
The dogmatic definitions (dogma means official teaching) and the canon laws of the ecumenical councils are understood to be inspired by God and to be expressive of His will for men. Thus, they are essential sources of Orthodox Christian doctrine.
Besides the seven ecumenical councils, there are other local church councils whose decisions have also received the approval of all Orthodox Churches in the world, and so are considered to be genuine expressions of the Orthodox faith and life. The decisions of these councils are mostly of a moral or structural character. Nevertheless, they too reveal the teaching of the Orthodox Church.
The Seven Ecumenical Councils
Nicea 1 325
Formulated the First Part of the Creed, defining the divinity of the Son of God
Constantinople I 381
Formulated the Second Part of the Creed, defining the divinity of the Holy Spirit
Ephesus 431
Defined Christ as the Incarnate Word of God and Mary as Theotokos
Chalcedon 451
Defined Christ as Perfect God and Perfect Man in One Person
Constantinople II 553
Reconfirmed the Doctrines of the Trinity and of Christ
Constantinople III 680
Affirmed the True Humanity of Jesus by insisting upon the reality of His human will and action
Nicea II 787
Affirmed the propriety of icons as genuine expressions of the Christian Faith
