First Council of Ephesus in the context of "BVM(RC)"

Theotokos (Koine Greek: Θεοτόκος) is a title of Mary, mother of Jesus, used especially in Eastern Christianity. The usual Latin translations are Dei Genitrix or Deipara (approximately "parent [fem] of God"). Common English translations are "Mother of God" or "God-bearer" – but these both have different literal equivalents in Ancient Greek: Μήτηρ Θεοῦ, and Θεοφόρος respectively.

The title has been in use since the 3rd century, and in the Liturgy of Saint James (4th century). The Council of Ephesus in AD 431 decreed that Mary is the Theotokos because her son Jesus is both God and man: one divine person from two natures (divine and human) intimately and hypostatically united.

Eutyches (Ancient Greek: Εὐτυχής; c. 375–454) or Eutyches of Constantinople was a presbyter and archimandrite at Constantinople. He first came to notice in 431 at the First Council of Ephesus, for his vehement opposition to the teachings of Nestorius. Eutyches was condemned for having adopted a polar opposite view of Nestorianism, where the two natures (Greek: hypostases) of Christ fuse together to form one, single Divine nature, dubbed Monophysitism. This was condemned at the Council of Chalcedon and Third Council of Ephesus. He himself, however, would reject this interpretation of his thought.

The Nestorian schism (a.d. 431–544) was a split between the Christian churches of Sassanid Persia, which affiliated with Nestorius, and those that later became the Catholic and Orthodox churches. The schism rose out of a Christological dispute, notably involving Cyril (Patriarch of Alexandria) and Nestorius (Patriarch of Constantinople).

The First Council of Ephesus in 431 and the Council of Chalcedon in 451 condemned Nestorius and his doctrine, which emphasized the radical distinctness between Christ's human and divine natures. That forced a breach between the churches that defended Nestorius and the state church of the Roman Empire, which caused the Church of the East, the Christian church of Sassanid Persia, to become known as the Nestorian Church, as it took the side of Nestorius.

The Second Council of Ephesus was a Christological church synod in 449 convened by Emperor Theodosius II under the presidency of Pope Dioscorus I of Alexandria. It was intended to be an ecumenical council, and it is accepted by the miaphysite churches, who view it as a valid continuation of the First Council of Ephesus if not an ecumenical council in its own right. The Second Council of Ephesus was explicitly repudiated by the next council, the Council of Chalcedon of 451. The Council of Chalcedon is recognized as the fourth ecumenical council by Chalcedonian Christians, and the Second Council of Ephesus was named the Latrocinium ("Robber Synod") by Pope Leo I; the Chalcedonian churches, particularly the Roman Catholic and Eastern Orthodox communions, continue to accept this designation, while the Oriental Orthodox repudiate it.

Both this council and that at Chalcedon dealt primarily with Christology, the study of the nature of Christ. Both councils affirmed the doctrine of the hypostatic union and upheld the orthodox Christian doctrine that Jesus Christ is both fully God and fully man. The Second Council of Ephesus decreed the formula of Cyril of Alexandria, stating that Christ is one incarnate nature [mia physis] (a qualitative description of the union of divinity and humanity), fully human and fully God, united without separation, without confusion, without mixture and without alteration. The Council of Chalcedon decreed that in Christ two natures exist, "a divine nature [physis] and a human nature [physis], united in one person [hypostasis], with neither division nor confusion".

Christianity in Asia has its roots in the very inception of Christianity, which originated from the life and teachings of Jesus in 1st-century Roman Judea. Christianity then spread through the missionary work of his apostles, first in the Levant and taking roots in the major cities such as Jerusalem and Antioch. According to tradition, further eastward expansion occurred via the preaching of Thomas the Apostle, who established Christianity in the Parthian Empire (Iran) and India. The very First Ecumenical Council was held in the city of Nicaea in Asia Minor (325). The first nations to adopt Christianity as a state religion were Armenia in 301 and Georgia in 327. By the 4th century, Christianity became the dominant religion in all Asian provinces of the Eastern Roman Empire.

After the First Council of Ephesus in 431 and the Nestorian Schism, the Nestorian Christianity developed. Nestorians began converting Mongols around the 7th century, and Nestorian Christianity was probably introduced into China during the Tang dynasty (618–907). Mongols tended to be tolerant of multiple religions, with several Mongol tribes being primarily Christian, and under the leadership of Genghis Khan's grandson, the great khan Möngke, Christianity was a small religious influence of the Mongol Empire in the 13th century.

John I of Antioch was Patriarch of Antioch (429 – 441). He led a group of moderate Eastern bishops during the Nestorian controversy. He is sometimes confused with John Chrysostom, who is occasionally also referred to as John of Antioch. John I gave active support to his friend Nestorius in the latter's dispute with Cyril of Alexandria. In the year 431, he arrived too late for the opening meeting of the First Council of Ephesus. Cyril, suspecting John I of using procrastinating tactics to support Nestorius, decided not to wait and convened the council without John I and his supporters, condemning Nestorius. When John I reached Ephesus a few days after the council had begun, he convened a counter-council that condemned Cyril and vindicated Nestorius.

In this controversy, according to Cyril, partisans of John I arrived at the Council before the Patriarch, and informed Cyril that John would be significantly late in arriving, and that Cyril should proceed with the Council in his absence, telling him, "our lord, the bishop John, commanded us to say to your reverence 'if I am late, do what you are doing.'" Cyril relates how he waited for John I for all of 16 days before finally beginning the Council in John's absence. Cyril's account of these events can be found in Chapter 3 of his Letter to Komarius and Others.