Council of Ephesus AD 431
Soon after the formation of the Church Heresy and variations in teachings were in existence in one form or other. During the Apostolic Period, they were settled with the mediation of the Apostles and Apostolic Synods and councils. The first of the council was the council of Jerusalem where the question of gentile inclusion in the church. However after the apostolic period this continued. Even today we have large number of theological systems varying ever so slightly. These movements arose powerfully around 400 A.D when Christianity became free from oppression and being a Christian became a prestige. In the year AD 425 Nestorius, a presbyter of the Church of Antioch became the Patriarch of Constantinople. He legitimately objected to the epithet of "Theokotos" "Mother of God" as applied to Mary since Mary was only the mother of the incarnation and not the mother who produced a God. This would imply that Mary was a Goddess. (We can now see how this epithet has led to the Marialotary and all the attempts to make Mary coredemptrix and equal in status with the trinity). In this sense he was indeed right. However he was understood to have propounded the concept that the Logos of God indwelt Jesus the man. Thus there were two natures in Jesus at the same time. If we are to judge by the Nestorian churches of today this was a misunderstanding. Cyril the Patriarch of Alexandria opposed this dual nature concept and insisted on the unity that Jesus was perfect man and perfect God without inconsistency. The controversy reached a climax when these Patriarchs excommunicated each other. However the conduct of the Ephesus council was totally deplorable that Nestorius was not ever given a hearing. By the time Nestorius arrived at Ephesus the council had voted against him and he was excommunicated and exiled. Its decision though universally accepted, the way the issue was treated is still considered deplorable. The Nestorius a genius theologian of the time was derided without even giving him a hearing. Nestorius certainly foresaw the consequence of the epithet Theokotos.
Council of Chalcedon AD 451
The fight went on and in AD 451 the Nestorians claimed a victory in the council of Chaldeons in the year 451. In this council it was declared that in Christ the two natures were hypostatically united, without mixture, confusion and divisibility. Cyril the Patriarch of Alexandria and John the Patriarch of Antioch finally reconciled. Nestorians adopted the name Chaldeon Church and the Patriarch took the title of Patriarch of Babylon. These in fights in the Middle East and Europe had its repercussions in India too. There exists a Chaldean church with few followings even today, though majority of the Christian churches remained faithful to the declarations of Nicea and Ephesus.