Nestorianism is a Christological heresy that emerged within the Church during the 5th century. It arose from attempts to provide a rational explanation for the incarnation of the divine Logos (the Second Person of the Holy Trinity) as the man Jesus Christ.
The core teaching of Nestorianism is that the human and divine essences of Christ are separate, suggesting the existence of two distinct persons in Christ: the man Jesus Christ and the divine Logos, which was said to have dwelt in the man. Due to this belief in two separate persons, Nestorians rejected applying terminology about God to the human actions of Christ. For example, they would reject phrases such as "God suffered" or "God was crucified", asserting that only the man Jesus Christ suffered.
Consequently, they also rejected the title Theotokos (Giver of birth to God) for the Virgin Mary. They argued that she gave birth only to the man Jesus, preferring the terms Christotokos (giver of birth to Christ) or Anthropotokos (giver of birth to a man).
Theodore of Mopsuestia was notably opposed to terms like "God was crucified", "God suffered", or "God was born", because he believed only the Man Jesus was born and that God simply dwelt in the Man Jesus, referring to Jesus as the Theophoros (Bearer of God).
Nestorian ideas were initially developed by Diodore of Tarsus in opposition to Apollinarianism. Diodore wrote that at the time of and after the Incarnation, the Divine and human natures of Jesus Christ were so divided that they maintained complete independence with no union whatsoever.
These ideas were further elaborated by Theodore of Mopsuestia (350-429), a scholar from the Antiochian theological tradition. Theodore taught that the human and Divine natures of Christ were so completely separate that there was only contact between them, but no union. He believed the Man Jesus was born naturally with faults, and that God the Logos united with him by Grace, foreknowing His triumph over sin. Theodore taught that Jesus was made worthy of being called Son of God after His triumph over sin and became God's tool for salvation.
Theodore's beliefs were heretical because, taken to their logical conclusion, they deny redemption and salvation; the question arises how the suffering of only a man could redeem the entire human race. Theodore was the first to oppose language that applied terms meant for God as descriptions of Jesus Christ, such as "God was crucified" or "God was born".
Nestorian ideas, originally confined to the writings of Diodore, Theodore of Mopsuestia, and their followers, became public through Nestorius, an Antiochian Priest-monk who became Archbishop of Constantinople in 428. Nestorius, along with his priest Anastasius, preached against the existence of one Theandric Person (Godman) in Christ, arguing for a division of persons and attacking the use of the term Theotokos, using Anthropotokos instead.
As you can imagine this caused controversy in Constantinople, where the faithful righty used Theotokos. To defend Anastasius, Nestorius preached Theodore of Mopsuestia's teachings, using the term Christotokos. Constantinopolitan theologians accused Nestorius of preaching the heresy of Paul of Samosata. Nestorius convened a council in Constantinople in 429, condemning those who disagreed with him.
The strongest opposition came from Saint Cyril of Alexandria, a theologian from the Alexandrian school. St Cyril wrote letters to Nestorius and the Emperor, outlining the Orthodox teaching and accusing Nestorius of heresy. He also informed Pope Celestine of Rome. A council in Rome in 430 condemned Nestorius and called for his deposition. St Cyril then held a council in Alexandria in 430, where he issued his renowned 12 Anathemas Against Nestorius.
These anathemas condemned specific Nestorian positions and affirmed the Orthodox belief in the true Godhead of Christ, the union by hypostasis, the singular nature of Christ as God and man together, and the consequence that Mary is truly Theotokos. Nestorius responded by publishing his own 12 anathemas, condemning those who attributed suffering and birth to God, believing this denied God due honour.
The Third Ecumenical Council (Ephesus, 431): To resolve the dispute, Emperor Theodore II called a council in Ephesus in 431. After waiting for absent delegates, St Cyril convened the Council with 200 bishops on June 22, 431. The Council reviewed the teachings of Nestorius, St Cyril, and the Fathers, concluding that Nestorius was teaching heresyand St Cyril's position was Orthodox. Nestorius refused to attend and accused St Cyril and others of holding an illegal council.
When John of Antioch and the Syrian bishops arrived, they refused to recognise the Council's decision and formed a rebel council with Nestorius, condemning St Cyril and Memnon of Ephesus and falsely accusing them of other heresies.
Initially, the Emperor ordered both councils closed and proceedings destroyed. However, St Cyril's council reconvened. They accepted the epistle of Pope Celestine and formally condemned Nestorius at their third session. They also found the condemnation by John of Antioch's council invalid.
Under the influence of the Nestorian party at court, the Emperor ordered Nestorius, Memnon, and St Cyril arrested. St Cyril appealed to Abba Dalmatius in Constantinople, who, with the faithful, marched to the palace and demanded the release of the Orthodox bishops and the condemnation of Nestorius. The people publicly proclaimed anathema on Nestorius. The Emperor eventually sided with the Orthodox position and ordered Nestorius's deposition. Deputies from both sides were sent to Chalcedon but could not agree, as the Syrian bishops rejected St Cyril's anathemas while agreeing in principle to Nestorius's condemnation.
Nestorianism After the Council
Despite the Council's decision, some in Syria did not accept it. A strong Nestorian party emerged in Syrian and Mesopotamian churches. Although the Syrian bishops eventually agreed to condemn Nestorius and confessed the unity of natures and Mary as Theotokos through the work of Paul of Emessa, they initially refused to condemn Nestorius personally or accept St Cyril's anathemas. Peace was restored when John of Antioch was convinced to condemn Nestorius, and St Cyril agreed to the Antiochian confession without retracting his anathemas.
John of Antioch worked to eliminate Nestorianism in the Eastern churches, using civil authorities to imprison Nestorian bishops. The Edessa theological school, which spread Nestorian ideas, was ordered destroyed by John of Antioch. Nestorian theologians fled to Persia after the school's destruction in 489. They formally broke with the Church in 499 at a council in Seleucia. This group formed the Chaldean or Assyrian Church, also known as the Assyrian Church of the East.
The Fifth Ecumenical Council (553): In the 6th century, debates continued, partly fuelled by Monophysites who accused the Church of restoring Nestorianism based on the unclear position on the writings of Theodore of Mopsuestia, Theodoret of Cyrrhus, and Ibo of Edessa. These writings became known as the Three Chapters.
The Fifth Ecumenical Council in 553 condemned Theodore of Mopsuestia as a heretic. It also condemned the writings of Theodoret against St Cyril and the letter of Ibo of Edessa to Marius the Persian. The persons of Theodoret and Ibo were not condemned, as they had repented of Nestorianism and condemned Nestorius.
Modern Nestorian Communities: Today, the main body historically linked to Nestorianism is the Assyrian Church of the East, which has jurisdiction primarily in Iraq and Eastern Iran, with its headquarters in Chicago, Illinois. This church is sometimes called the _Assyrian Orthodox Church_ but is distinct from other churches like the Syriac Orthodox Church or the Chaldean Catholic Church.
The split between the Assyrian Church and the broader Church began at the Council of Seleucia in 410 with a declaration of independence from Antioch, solidifying after the condemnation of Nestorius and the destruction of the Edessa school. Other factors included their location in the Persian Empire and an influx of Nestorian Christians fleeing persecution.
A significant schism occurred in the 15th century over the issue of hereditary succession for the Patriarchate, leading to a rival Patriarch who entered communion with the Roman Catholic Church. This group eventually became known as the Chaldean Catholic Church, an Eastern Catholic body. The hereditary line in Alqosh died out in 1804, and that church accepted the authority of the Chaldean patriarchs. Another schism related to hereditary succession occurred in 1964, creating rival patriarchates. Although hereditary succession has ended, the rift persists.
The Assyrian Church of the East today usually denies teaching Nestorianism. A "Common Christological Declaration" signed by Mar Dinkha IV and Pope John Paul II in 1994 affirmed a shared understanding of the Son of God. The Assyrian Church halted anathemas of other churches in its liturgy in 1997. However, the Assyrian Church of the East recognises Theodore of Mopsuestia as a saint, whose Christology was repeatedly condemned as Nestorian by the Orthodox Church.
Crypto-Nestorianism in Modern Theology
Modern Evangelical Protestants, in their refusal to venerate the Virgin Mary and denying the use of the term Theotokos, engage in a form of Crypto-Nestorianism. Their argument that Mary only gave birth to the man Jesus separates the human and Divine persons in the God-man Jesus Christ. A grave error stemming from a failure to grasp the intricacies of Christology and the doctrine of the Incarnation. A correct understanding of the Virgin Mary is necessary for a correct understanding of Jesus Christ: if Mary is not Theotokos, then Christ is not the God-man; conversely, if Christ is the God-man, then Mary is Theotokos.