NESTORIUS (d. c. 451), Syrian ecclesiastic, patriarch of Constantinople from 428 to 431, was a native of Germanicia at the foot of Mount Taurus, in Syria. The year of his birth is unknown. He received his education at Antioch, probably under Theodore of Mopsuestia. As monk in the neighbouring monastery of Eupre pius, and afterwards as presbyter, he became famous in the diocese for his asceticism, his orthodoxy and his eloquence. He was nomi nated by Theodosius II. patriarch of Constantinople, and was con secrated on April 1o, 428. He immediately set to work to extirpate heresy in his diocese, beginning by the suppression of the assem blies of the Arians. These, by a bold stroke of policy, anticipated his action by themselves setting fire to their meeting-house, Nes torius being forthwith nicknamed "the incendiary." His repres sion of the Novatians and the Quartodecimans led to serious dis turbances at Sardis and Miletus. The toleration the followers of Macedonius had long enjoyed was also broken, the recently settled Pelagians alone finding any respite. One of the practices assailed by Nestorius was the custom, which had become almost universal in Constantinople, of bestowing the epithet 0E0T6KOS "Mother of God," upon Mary the mother of Jesus. From Antioch Nestorius had brought along with him to Constantinople a co-presbyter named Anastasius, who enjoyed his confidence and is called by Theophanes his "syncellus." This Anastasius, in a pulpit oration which the patriarch himself is said to have prepared for him, caused great scandal to the partisans of the cult of Mary by say ing, "Let no one call Mary the mother of God, for Mary was a human being; and that God should be born of a human being is impossible." Cyril (q.v.) of Alexandria seized his opportunity. He stirred up his own clergy, he encouraged the dissidents at Constantinople, he addressed himself to the sister and wife of the emperor, and he bribed the officials of the court. He also sent to Rome a careful selection of Nestorius's sayings and sermons. Nestorius himself,
on the other hand, having occasion to write to Pope Celestine I. about the Pelagians (whom he was not inclined to regard as heretical), gave from his own point of view an account of the disputes which had recently arisen within his patriarchate. Celes tine naturally resented any questioning of the Roman decision concerning the Pelagians, and was jealous of the growing power of the Constantinople see. In a synod which met in 43o, he decided in favour of the title 0E0761COS, bade Nestorius retract his erroneous teaching, on pain of instant excommunication, and entrusted the execution of this decision to the patriarch of Alexandria.
In this situation of affairs the demand for a general council be came irresistible, and accordingly Theodosius and Valentinian III. issued letters summoning the metropolitans of the Catholic church to meet at Ephesus at Whitsuntide 431, each bringing with him some able suffragans. Nestorius, with sixteen bishops and an armed following, Cyril with fifty bishops, Juvenal of Jerusalem, and Flavian of Thessalonica arrived. John of Antioch was delayed on his journey, and wrote requesting that the opening of the synod should not be delayed on his account. Cyril and his friends assembled in the church of the Theotokos on June 22, and sum moned Nestorius to give an account of his doctrines. He replied that he would appear when all the bishops were assembled ; and the imperial commissioner, Candidian, formally protested against the opening of the synod. Cyril and the 159 bishops who were with him nevertheless proceeded to read the imperial letter of convoca tion, and afterwards the letters which had passed between Nes torius and Cyril. The entire assembly then cried anathema on Nestorius and his doctrines, and the decree of his exclusion from the episcopate and from all priestly communion was solemnly read and signed by all present. The accused and his friends never had a hearing.