Nestorianism

Central to Christianity is the belief that Jesus is both the Son of God and lived on earth as a human being. The orthodox interpretation of this belief is that Jesus is both fully divine and fully human, having two natures, a divine nature and a human nature, distinct from, but very closely related to, each other.

Nestorianism, i.e., the teaching of Nestorius (died ?451), Patriarch of Constantinople (428-431), accepts that Jesus has both a divine and a human nature, but holds that his two natures are more loosely related to each other than is claimed by the orthodox view. Nestorianism, in the eyes of the orthodox, over-emphasises the distinctness of Jesus' two natures and thus threatens his unity as a single person. But Nestorius' position also had other implications which were unwelcome to orthodox Christians. For example, he argued that since Jesus' mother Mary was, strictly speaking, the mother only of Jesus' human nature and not of his divine nature, she ought not to be accorded the honorofic title of 'Mother of God' (θεοτόκος, theotokos, God-bearer or Mother of God).

Nestorianism was condemned as heretical by the third ecumenical Council of bishops meeting at Ephesus in 431, and condemned again, along with Monophysitism, by the fourth ecumenical Council at Chalcedon in 451. It nonetheless continued to flourish; and on the eastern borders of the Roman Empire many churches which were sympathetic to Nestorius' teaching separated from the rest of the Christian Church to form the Nestorian Church.

Nestorianism, like the orthodox view, is a form of Dyophysitism - pronounced with the stress on the second syllable, dy-OFF-i-sai-tizm IPA: /daɪ 'ɒ fɪ ,saɪ tɪzm/ - i.e., the belief that Jesus has two natures. It stands in opposition to Monophysitism, i.e., the view that Jesus has a single nature.