NESTORIANISM is a doctrinal position on the nature of Jesus Christ. In its extreme form the doctrine has been condemned by Christian councils, but the ideas associated with Nestorianism have come to represent one of the two main traditions of Christological thought in Christianity and have been ably defended and articulated by successive generations of Christian thinkers. The name goes back to Nestorius, a patriarch of Constantinople in the early fifth century who was deposed at the Council of Ephesus in 431 and exiled to Egypt in 436. Nestorius was not, however, an original thinker, and the theological views that came to be associated with his name had arisen late in the fourth century among Christian thinkers in eastern Asia Minor and Syria (in the vicinity of ancient Antioch), notably Diodore of Tarsus and Theodore of Mopsuestia. The distinctive features of Nestorianism can be made clear by contrasting it with...