The reasons which brought the revised creed into prominence at Chalcedon are still obscure.
At the council of Chalcedon in 451 it was declared that in the person of Christ are united two complete natures, divine and human,which retain after the union all their properties unchanged.
The synod of Chalcedon in 451, following the lines of Pope Leo I.'s famous letter, endeavoured to steer a middle course between the so-called Nestorian and Eutychian positions.
The march of Arab conquest kept the Armenians friendly to Byzantium for a few years; but in 718 the catholicus John of Odsun ascended the throne and at the council of Manazkert in 728 repeated and confirmed the anathemas against Chalcedon and the tome of Leo, that had been first pronounced by the catholicus Babken in 491 at a synod held in Valarshapat by the united Armenian, Georgian or Iberian, and Albanian churches.
Having made a fortune by teaching and lecturing in Chalcedon he spent the rest of his life chiefly at Athens, where he died.
All these circumstances point to the council of Chalcedon (451).
The Melchites therefore are those who accept the decrees of Ephesus and Chalcedon as distinguished from the Nestorians and Jacobite Church (qq.v.).
On the advice of Acacius, the energetic patriarch of Constantinople, Zeno issued the Henotikon edict (482), in which Nestorius and Eutyches were condemned, the twelve chapters of Cyril accepted, and the Chalcedon Definition ignored.
Unfortunately the acts of the council have been lost, but they were quoted at the council of Chalcedon in A.D.
Hence the Nestorians, who insisted upon the duality of the natures to such a degree as to lose sight of the unity of the person, and who rejected the term Theotokos, repudiated the decrees both of Ephesus and of Chalcedon, and upon the promulgation of the decrees of Chalcedon formally separated from the church.