What is "nestorianism"

Nestorianism \Nes*to"ri*an*ism\, n. The doctrines of the Nestorian Christians, or of Nestorius.

Nestorianism is a Christological doctrine that emphasizes a distinction between the human and divine natures of Jesus. It was advanced by Nestorius (386–450), Patriarch of Constantinople from 428 to 431, influenced by Nestorius's studies under Theodore of Mopsuestia at the School of Antioch.

Nestorius's teachings brought him into conflict with other prominent church leaders, most notably Cyril of Alexandria, who criticized especially his rejection of the title Theotokos ("Bringer-forth of God") for Mary, the mother of Jesus. Nestorius and his teachings were eventually condemned as heretical at the Council of Ephesus in 431 and the Council of Chalcedon in 451, which led to the Nestorian Schism; churches supporting Nestorius broke with the rest of the Christian Church.

Following that, many of Nestorius's supporters relocated to the Sasanian Empire, where they affiliated with the local Christian community, known as the Church of the East. Over the next decades the Church of the East became increasingly Nestorian in doctrine, leading to it becoming known alternatively as the Nestorian Church.