First seven ecumenical councils

In the history of Christianity, the first seven ecumenical councils include the following: the First Council of Nicaea in 325, the First Council of Constantinople in 381, the Council of Ephesus in 431, the Council of Chalcedon in 451, the Second Council of Constantinople in 553, the Third Council of Constantinople from 680 to 681 and finally, the Second Council of Nicaea in 787. All of the seven councils were convened in what is now the country of Turkey.

These seven events represented an attempt by Church leaders to reach an orthodox consensus, restore peace^[1] and develop a unified Christendom.^[2] Among Eastern Christians the Eastern Orthodox, Oriental Orthodox, and Church of the East (Assyrian) churches and among Western Christians the Roman Catholic, Anglican, Utrecht and Polish National Old Catholic, and some Scandinavian Lutheran churches all trace the legitimacy of their clergy by apostolic succession back to this period and beyond, to the earlier period referred to as the Early Church.

This era begins with the First Council of Nicaea in AD 325, convened by the emperor Constantine I following his victory over Licinius and consolidation of his reign over the Roman Empire. Nicaea I enunciated the Nicene Creed that in its original form and as modified by the First Council of Constantinople of 381 was seen by all later councils as the touchstone of orthodoxy on the doctrine of the Trinity.

The Eastern Orthodox and Roman Catholic Churches accept all seven of these councils as legitimate ecumenical councils. The Non-Chalcedonian Oriental Orthodox Churches accept only the first three, while the Non-Ephesian Church of the East accepts only the first two. There is also one additional council, the so-called Quinisext Council of Trullo held in AD 692 between the sixth and seventh ecumenical councils, which issued organizational, liturgical and canonical rules but did not discuss theology. Only within Eastern Orthodoxy is its authority commonly considered ecumenical; however, the Orthodox do not number it among the seven general councils, but rather count it as a continuation of the fifth and sixth. The Roman Catholic Church does not accept the Quinisext Council,^[3][4] but both the Roman magisterium as well as a minority of Eastern Orthodox hierarchs and theological writers consider there to have been further ecumenical councils after the first seven (see the Fourth Council of Constantinople, Fifth Council of Constantinople, and fourteen additional post-schism ecumenical councils canonical for Catholics).