Ephesus had decisively established that Our Lady was the “Theotokos”, the God-bearer, or, more colloquially, the Mother of God. Nestorius had been deposed and sent into exile. But the split occasioned there between the Antiochenes and the Alexandrians had not been easily healed. In part the difficulty was one of language. The language of Antioch ended up making Jesus sound like a very special human being; some of the language coming out of Alexandria made Him sound like God assuming a human persona. It is often the case in Church history that once a disagreement like the one at Ephesus occurs, a schism follows, and that it did not on this occasion, owed much to St Cyril’s willingness to try to find a formula of reconciliation. Contrary to the view taken of his by his critics, the great patriarch was, the main issue being conceded, happy to explore options which would allow Alexandria and Antioch to come back into full communion with each other.

In 433 John of Antioch and Cyril of Alexandria agreed on a ‘Formula of Union’:

We confess, then, our lord Jesus Christ, the only begotten Son of God perfect God and perfect man of a rational soul and a body, begotten before all ages from the Father in his godhead, the same in the last days, for us and for our salvation, born of Mary the virgin, according to his humanity, one and the same consubstantial with the Father in godhead and consubstantial with us in humanity, for a union of two natures took place. Therefore we confess one Christ, one Son, one Lord. According to this understanding of the unconfused union, we confess the holy virgin to be the mother of God because God the Word took flesh and became man and from his very conception united to himself the temple he took from her. As to the evangelical and apostolic expressions about the Lord, we know that theologians treat some in common as of one person and distinguish others as of two natures, and interpret the god-befitting ones in connection with the godhead of Christ and the lowly ones with his humanity.

So, although, as the Antiochenes wanted, it affirmed ‘two natures’ , it also did what the Alexandrians wanted and stressed the union of those natures in ‘one person’. Some of Cyril’s more zealous supporters were unhappy with the formula and thought it conceded too much to the other side, but such was the great patriarch’s prestige and learning that they said little whilst he loved. But in 444 he died. His successor, Dioscorus, was among those who thought Cyril had conceded too much, and as we shall see, he enjoyed considerable success in 449 in asserting his views against those of Antioch and Constantinople. His opponents wanted the Emperor to summon a new Council to review the work of the 449 meeting, but the Emperor refused, and whilst he lived, Dioscorus faced no challenge.

In the summer of 451, the Emperor Theodosius II fell off his horse and was fatally injured. History is always being changed by something or other, but here things shifted decisively for the early Church. His sister, the Empress Pulcheria, who had been regent before his reign, took on the role again and married a man called Marcian. She wanted the question which had arisen as part of the Council of Ephesus – that of the nature of the union in Christ – settled. She had been a great admirer of Cyril of Alexandria and was, herself, famously devout. She had taken a vow of perpetual virginity (Marcian had to accept that as part of the marriage contract), and she had a deep veneration for the Theotokos. The continuing disputes within the church over Christological questions were, she thought, divisive and should be solved. The calling of a new Council allowed the opponents of Dioscorus to move the ground onto his conduct of the previous Council – and this, as we shall see, was an unwelcome development.