Ephesus, Council of, 431, 3d ecumenical council, convened by Theodosius II, emperor of the East, and Valentinian III, emperor of the West, to deal with the controversy over Nestorianism. Adherents of both parties attended; St. Cyril, patriarch of Alexandria, had the support of Pope Celestine I and most of Christendom; Nestorius was backed by Theodosius and the Antiochene hierarchy. The council, late in starting, was opened by St. Cyril before the Antiochene bishops arrived. It anathematized Nestorius and his views. The Antiochenes arrived and, accusing Cyril of deliberately rushing the vote, deposed him. Soon afterward the papal legates arrived and the council reconvened, reaffirmed its position, and excommunicated the Antiochenes. The controversy continued until Theodosius held a hearing at Chalcedon between the disputants. He exiled Nestorius and ordered the consecration of a new patriarch of Constantinople; the council then broke up. Its chief dogmatic pronouncement was that from the very words of the Nicene Creed it follows that Mary may be called Mother of God, for the perfect coherence of godhead and manhood in Christ prevents any separation of natures such as Nestorius implied. This doctrine was later defined further (see Chalcedon, Council of). For the Robber Synod (Latrocinium) of Ephesus, see Eutyches.