The Council of Chalcedon (kælˈsiːdən,_ˈkælsɪdɒn; Concilium Chalcedonense) was the fourth ecumenical council of the Christian Church. It was convoked by the Roman emperor Marcian. The council convened in the city of Chalcedon, Bithynia (modern-day Kadıköy, Istanbul, Turkey) from 8 October to 1 November 451 AD. The council was attended by over 520 bishops or their representatives, making it the 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).
As recorded by American Christian scholar Jaroslav Pelikan, it was stated:We all teach harmoniously [that he is] the same perfect in godhead, the same p