The Chalcedonian Definition (also called the Chalcedonian Creed or the Definition of Chalcedon) is a declaration of Christ's nature, adopted at the Council of Chalcedon in AD 451. Chalcedon was an early centre of Christianity located in Asia Minor (modern Turkey). The council was the fourth of the ecumenical councils that are accepted by Chalcedonian churches which include the Catholic, Eastern Orthodox, Lutheran, Anglican and Reformed churches.It was the first council not to be recognised by any Oriental Orthodox church; for this reason these churches may be classified as Non-Chalcedonian.



The Council of Chalcedon (; Latin: Concilium Chalcedonense; Greek: Σύνοδος τῆς Χαλκηδόνος, Synodos tēs Chalkēdonos) was the fourth ecumenical council of the Christian Church. It was convoked by the Byzantine emperor Marcian. The council convened in the city of Chalcedon, Bithynia (modern day Kadikoy, Turkey) from 8 October to 1 November 451AD. The council was attended by 520 bishops or their representatives making it largest and best-documented of the first seven ecumenical councils. The principal purpose of the council was to re-assert the teachings of the ecumenical Council of Ephesus against the heresies of Eutyches and Nestorius. Such heresies attempted to dismantle and separate Christ's divine nature from his humanity (Nestorianism) and further, to limit Christ as solely divine in nature (Monophysitism.)