1st Council - 325 - Convened in Niacea against Arian heresy, which stated that Christ wasn't divine but created. The Nicene Creed was adopted stating in part: "light of light, true God of God, begotten not made of one essence with Father...".
2nd Council - 381 - Convened in Ephesus against Macedonian heresy which stated the Holy Spirit was created by the Son and subordinate to the Father and Son. The Nicene Creed stated: "I believe in the Holy Spirit, the Lord, the Giver of Life, Who proceedeth from the Father; Who with Father and the Son together is worshiped and glorified...".
3rd Council - 431- Convened at Ephesus against the heresy of Nestorius, which stated that Christ two distinct natures and that God's Mother wasn't the Mother of God or Theotokos or (God-bearer) but Mother of Christ (Christ-bearer). Nestorians tried to rationalize the incarnation of the Divine Logos.
4th Council - 451 - Convened at Chalcedon against the Monophysite heresy which stated that Christ had only one nature.
5th Council - 553 - Convened at Constantinople to reinterpret the Chalcedonian decrees, to explain more constructively the two natures of Christ and to anathematize parts of Origen's teachings.
Chalcedonian decrees addressed the Monophysites who stated that "Christ was in two natures, unconfusedly, unchangeably" and also at the followers of Nestorius who proclaimed "One and the same Son...indivisibly, inseparably".
But Chalcedon was more than a defeat for Alexandrian theology: it was a defeat for Alexandrian claims to rule supreme in the east. Canon XXIII of Chalcedon confirmed Canon III of Constantinople, assigning to New Rome the place next in honour after Old Rome. The council also freed Jerusalem from the jurisdiction of Caesarea and gave it the fifth place among the great sees. The system later known among Orthodox as the Pentarchy was now complete, whereby five great sees in the Church were held in particular honour, and a settled order of precedence was established among them: in order of rank, Rome, Constantinople, Alexandria, Antioch, Jerusalem. A11 five claimed Apostolic foundation. The first four were the most important cities in the Roman Empire; the fifth was added because it was the place where Christ had suffered on the Cross and risen from the dead. The bishop in each of these cities received the title Patriarch. The five Patriarchates between them divided into spheres of jurisdiction the whole of the known world, apart from Cyprus, which was granted independence by the Council of Ephesus and has remained self-governing ever since.
6th Council - 680 - Convened at Constantinople against the Monothelites, who argued that although Christ has two natures, yet since He is a single person, He has only one will. The Council replied that if He has two natures, then He must also have two wills. The Monothelites, it was felt, impaired the fullness of Christ's humanity, since human nature without a human will would be incomplete, a mere abstraction. Since Christ is true man as well as true God, He must have a human as well as a divine will.
7th Council - 787 - Convened at Nicea against the Iconoclast heresy which condemned all religious art of humans or God but deeper issues were involved: the character of Christ's human nature, the Christian attitude towards matter, the true meaning of Christian redemption.
The Iconoclasts may have been influenced from the outside by Jewish and Muslim ideas, and it is significant that three years before the first outbreak of Iconoclasm in the Byzantine Empire, the Muslim Caliph Yezid ordered the removal of all icons within his dominions. But Iconoclasm was not simply imported from outside; within Christianity itself there had always existed a 'puritan' outlook, which condemned icons because it saw in all images a latent idolatry. When the Isaurian Emperors attacked icons, they found plenty of support inside the Church.