A heretical teaching that understood Christ to be two persons, one human and one divine. It also held that Mary was not the Mother of God ("Theotokos"), but only the mother of the human Christ. It was named for Nestorius (c. 381-c. 451), who was Patriarch of Constantinople (428-431). Nestorianism was condemned at the Council at Ephesus (431), under the presidency of St. Cyril of Alexandria. The Council also upheld Mary's title Theotokos, acknowledging Jesus Christ to be "one and the same" divine person. The Chalcedonian Definition (451) subsequently affirmed that Jesus Christ is at once truly God and truly man in two natures "without separation, without division" (see BCP, p. 864). Nestorius was condemned, deposed, and banished to a monastery. His works were burned by imperial order in 436. Although Nestorius clearly opposed the use of Mary's title Theotokos, it is debatable how much he actually believed of the condemned heresies of Nestorianism. See Chalcedonian Definition.
Glossary definitions provided courtesy of Church Publishing Incorporated, New York, NY,(All Rights reserved) from "An Episcopal Dictionary of the Church, A User Friendly Reference for Episcopalians," Don S. Armentrout and Robert Boak Slocum, editors.