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Christology

The schism between Oriental Orthodoxy and the adherents of Chalcedonian Christianity was based on differences in Christology. The First Council of Nicaea, in 325, declared that Jesus Christ is God, that is to say, " consubstantial " with the Father. Later, the third ecumenical council, the Council of Ephesus, declared that Jesus Christ, though divine as well as human, is only one being, or person (hypostasis). Thus, the Council of Ephesus explicitly rejected Nestorianism, the Christological doctrine that Christ was two distinct persons, one divine (the Logos) and one human (Jesus), who happened to inhabit the same body.

Twenty years after Ephesus, the Council of Chalcedon reaffirmed the view that Jesus Christ was a single person, but at the same time declared that this one person existed "in two complete natures", one human and one divine.

At times, Chalcedonian Christians have referred to the Oriental Orthodox as being monophysites —that is to say, accusing them of following the teachings of Eutyches (c. 380 – c. 456), who argued that Jesus Christ was not human at all, but only divine. Monophysitism was condemned as heretical alongside Nestorianism, and to accuse a church of being monophysite is to accuse it of falling into the opposite extreme from Nestorianism. However, the Oriental Orthodox themselves reject this description as inaccurate, having officially condemned the teachings of both Nestorius and Eutyches. They define themselves as miaphysite instead, holding that Christ has one nature, but this nature is both human and divine.