Second Council of Ephesus, (431), the third ecumenicalcouncil of the Christian church, meeting in Ephesus to clarify doctrine relating to the personhood (hypostasis) of Christ and combat the rise of Nestorianism. Pope Celestine I commissioned St. Cyril, patriarch of Alexandria, to conduct proceedings against Nestorius, his longtime adversary, whose doctrine of two persons in Christ the pope had previously condemned. The key religious argument involved the relation of the divine and human within Jesus Christ: Cyril emphasized the unity of the two in one person, whereas Nestorius so emphasized their distinctness that he seemed to be splitting Christ into two persons acting in concert.
The conflict came to the fore over Cyril’s insistence that the Virgin Mary be called Theotokos (Greek: “God-bearer”) to describe the intimate union of the two natures in the Incarnation. Nestorius refused to accept such terminology, insisting that this compromised the reality of Christ’s human nature. His stance, however, was seen as a denial of the unity of the God-man, and their dispute was referred to the council at Ephesus in 431. Armed with a commission to represent Celestine I as well as himself, Cyril convened the council and condemned Nestorius. The council affirmed “that the Word, uniting to himself in his person the flesh animated by a rational soul, became man.”
Cyril had not waited, however, for the arrival of certain bishops from the East, particularly from the see of Antioch, where Nestorius had lived before he became bishop of Constantinople. When they did reach Ephesus, they set up a rival synod under John of Antioch and excommunicated Memnon, the bishop of Ephesus, along with Cyril. Papal recognition of Cyril’s council was eventually obtained, however, and Nestorius was formally deposed as the bishop of Constantinople and banished as a heretic. Even so, the dispute continued, and peace in the church was restored only in 433, when Cyril accepted a statement, representing a compromise with Antioch, that emphasized the distinctness of the two natures within the one person of Christ.
Nestorius was born of Persian parents. He studied at Antioch (now in Turkey), probably as the pupil of Theodore, bishop of Mopsuestia. He became a monk at the nearby monastery of St. Euprepius and, after being ordained a priest, acquired a great reputation for asceticism, orthodoxy, and eloquence. Owing to this reputation, Nestorius was nominated by the Eastern Roman emperor Theodosius II to become bishop of Constantinople in 428. His debut was a stormy one, however, for he immediately set to work extirpating heretics of every sort, showing leniency only to Pelagians.
A crisis developed when Nestorius’s domestic chaplain, Anastasius, on November 22, 428, preached a sermon in which he objected to the title Theotokos (“God-Bearer”) as applied to Mary. Many were scandalized, for the term had long been in use. Nestorius, who had already expressed doubts on the subject, supported Anastasius and on Christmas Day began a series of addresses arguing that Mary was not Theotokos. Nestorius considered that, unless carefully qualified, the term Theotokos as applied to Mary compromised Christ’s full humanity. To many people it seemed that Nestorius himself was denying the divinity of Christ and regarding him as a mere man who had been adopted by God as his son. In the resulting controversy, Nestorius’s opponents found an ally in St. Cyril, bishop of Alexandria, whose intervention set in motion a series of events that finally led to Nestorius’s downfall.
Cyril’s motive was twofold. He sincerely believed that Nestorius was undermining the purity of the faith; Nestorius’s refusal to style Mary as Mother of God seemed to Cyril to deny the unity of the God-man. As bishop of Alexandria, Cyril also was eager to belittle the rival see of Constantinople, as his immediate predecessor, Theophilus, had done in the case of St. John Chrysostom. Theological and political considerations were thus combined.
Both sides appealed to Pope Celestine I, who had already been offended by Nestorius’s tactlessness. In August 430 Celestine held a church council in Rome which decided that correct Christology required the use of the term Theotokos and requested Nestorius to disown his errors. When Cyril, who had been authorized to execute the sentence upon Nestorius, produced a string of provocative anathemas for him to subscribe to or face excommunication, Nestorius and his allies took alarm, and he persuaded the emperor Theodosius to convene a general church council. It was Nestorius’s hope that the council would result in the condemnation of Cyril. When the council met at Ephesus in 431, however, Nestorius found himself hopelessly outmaneuvered by Cyril.
Nestorius’s teaching was condemned and he himself was deposed from his see. Theodosius was induced to ratify these decisions, and Nestorius was relegated to his former monastery near Antioch. After languishing there in exile for four years (431–435), he was transferred to the Great Oasis (now the Oasis of Khārijah) in the Libyan Desert about 436 and was later removed to Panopolis in Upper Egypt. During his exile, he wrote the Book of Heraclides of Damascus, which he intended as a defense of his teaching and a history of his life. The sole treatise from his pen to have survived, it was discovered in 1895 in a Syriac translation. Nestorius died in Panopolis about 451, protesting his orthodoxy.
Nestorius is regarded as one of the principal heretics in Christology, and the heresy traditionally linked with his name, Nestorianism, was formally condemned at the church councils of Ephesus (431) and Chalcedon (451). Nestorianism, as it was understood at the time, so insisted upon the full humanity of Christ’s human nature that it was believed to divide him into two persons, one human and the other divine. Whereas orthodox Christology holds that Christ has two natures, divine and human, ineffably united in one person, or hypostasis, Nestorianism so stresses their independence as to suggest that they are in effect two persons, or hypostases, loosely joined by a moral union. Nestorianism envisages the divine Word as having associated with itself at the Incarnation a complete, independently existing man. From the orthodox point of view, Nestorianism therefore denies the reality of the Incarnation and represents Christ as a God-inspired man rather than as God-made-man. Since the 5th century all the principal branches of the Christian church have united in condemning Nestorianism and have affirmed that Christ is a single person, at once wholly human and wholly divine. Even the so-called Nestorian church is not Nestorian in the strict sense, though it venerates Nestorius and refuses to accept the title Theotokos.
Are you a student?
Get a special academic rate on Britannica Premium.
It is questionable, however, whether Nestorius himself ever taught, or intended to teach, the heresy named for him. Indeed, he repudiated such views, and Cyril’s attacks on him were based on a misunderstanding. The fact is that Nestorius repeatedly affirmed the perfect unity of the incarnate Christ, and he repudiated any suggestion of there being two persons existing side by side in his being. Nestorius can be better understood as the victim of his own intolerant personality and crudely provocative rhetoric and as having been the loser in one of the rivalries between great episcopal sees that were a feature of the time.
What Nestorius actually taught was a prosopic union. The Greek term prosōpon means the external, undivided presentation, or manifestation, of an individual that can be extended by means of other things—e.g., a painter includes his brush within his own prosōpon. So the Son of God used manhood for his self-manifestation, and manhood was therefore included in his prosōpon, so that he was a single object of presentation.
Nestorianism was crushed within the Roman Empire but survived outside its frontiers. The Christian church in Persia adopted it, largely to obtain the protection of its rulers by assuring them that its religion was not that of their enemies the Romans. Nestorianism continues today, though its adherents are few, with groups being found in Iraq, India, Iran, Syria, and North and South America.
Our editors will review what you’ve submitted and determine whether to revise the article.
verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies.
Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style
The Editors of Encyclopaedia Britannica. "Second Council of Ephesus". Encyclopedia Britannica, 17 Jun. 2025, https://www.britannica.com/event/Second-Council-of-Ephesus. Accessed 28 June 2025.
Our editors will review what you’ve submitted and determine whether to revise the article.
print
Print
Please select which sections you would like to print:
verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies.
Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style
Kelly, John N.D.. "Nestorius". Encyclopedia Britannica, 18 Jun. 2025, https://www.britannica.com/biography/Nestorius. Accessed 28 June 2025.