The contentious Third Ecumenical Council was held in the ancient city of Ephesus in Asia Minor on this day in 431. It had been called to resolve a doctrinal controversy that had split the entire church into two warring camps.
The teachings of Nestorius, the prominent Archbishop of Constantinople, had been challenged by Cyril, the equally prominent Archbishop of Alexandria. The emperor Theodosius, who called the Council, believed that the strength of his empire depended upon true worship of God without the intermingling of any manner of falsehood. Thus, he was determined not to allow the controversy to remain unresolved.
The conflict actually, originated in the school of Antioch, when Diodorus and Theodore, bishop of Mopsuestia argued that the human and divine natures of Christ could not have been united from the moment of conception in the womb of Mary. The orthodox position had always been that Mary was the Theotokos—literally, the God Bearer or Mother of God. The church had thus always taught that though the Virgin Mary was not the progenator of the eternal and indivisible Trinity, she was nevertheless the mother, of the incarnate second Person of the Trinity, the God-Man, Jesus. Thus Theotokos was an important honorific title intended to emphasize the union of the two natures of Christ. Nestorius though, taking his cues from his mentors in Antioch, refused to accept the title Theotokos arguing that it rationally belittled the character and nature of Christ’s humanity.
The Council at Ephesus opened before Nestorius and his followers were able to arrive to explain their position more fully. Thus, they were never actually able to answer the charges against them. Nevertheless, the heresy seemed clear-cut. As a result, Cyril, with the agreement of Theodosius and Celestine, the Archbishop of Rome, issued a series of anathemas. In effect, he served as both accuser and judge—but it was more than evident to most of the other two hundred theologians, pastors, and bishops that Nestorianism undermined an essential aspect of the very nature of Christ, the incarnation, and the Trinity.