The Council of Ephesus was convened in 431 to combat the heretical teachings of Nestorius. Nestorius denied the humanity of Christ. Though quickly condemned by the papacy, his teachings gained a wide following in parts of the East. Attended by Saint Cyril of Alexandria who spoke for orthodoxy.For lengthier explanations, see the Catholic Encyclopedia articles on the Council of Ephesus and Nestorius and his teachings.