Eutyches

[3] The patriarch of Constantinople, Nestorius, having asserted that Mary ought not to be referred to as the "Mother of God" (Theotokos in Greek, literally "God-bearer"),[4] was denounced as a heretic; in combating this assertion of Patriarch Nestorius, Eutyches was claimed to have declared that Christ was "a fusion of human and divine elements",[4] causing his own denunciation as a heretic seventeen years after the First Council of Ephesus at the 448 AD Synod of Constantinople, and later again in 451 at the Council of Chalcedon.

He was accused of heresy by Domnus II of Antioch and Eusebius, bishop of Dorylaeum at a synod presided over by Flavian at Constantinople in 448.

Overawed by the presence of a large number of Egyptian monks, the council not only reinstated Eutyches to his office but also deposed Eusebius, Domnus, and Flavian, his chief opponents.

The council's judgment conflicted with the opinion of the bishop of Rome, Leo, who, departing from the policy of his predecessor Celestine, had written very strongly to Flavian in support of the doctrine of the two natures and one person.

In October 451, Marcian and Pulcheria summoned a council (the fourth ecumenical) which met at Chalcedon, which Dioscorus attended and at which he was condemned.

That previous synod's proceedings were annulled and, in accordance with the more miaphysite strand in the teaching of Cyril of Alexandria, it was declared that the two natures are united in Christ (without any alteration, absorption or confusion) and 'come together to form one person and one hypostasis.'