First seven Ecumenical Councils

In the history of Christianity, the first seven ecumenical councils, from the First Council of Nicaea (325) to the Second Council of Nicaea (787), represented an attempt by Church leaders to reach an orthodox consensus, restore peace and develop a unified Christendom.Eastern Orthodox, Oriental Orthodox, Nestorian, and Roman Catholics, all trace the legitimacy of their clergy by apostolic succession back to this period and beyond, to the earlier period referred to as Early Christianity.

This era begins with the First Council of Nicaea, which enunciated the Nicene Creed that in its original form and as modified by the First Council of Constantinople of 381 was seen as the touchstone of orthodoxy on the doctrine of the Trinity.

The Church of the East (Nestorian) accepts the first two of the seven councils, but rejects the third, the Council of Ephesus (431), and subsequent councils. The Quinisext Council (692), which attempted to establish the Pentarchy and which is not generally considered one of the first seven ecumenical councils, is not accepted by the Roman Catholic Church, which also considers that there have been many more ecumenical councils after the first seven.

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