The Anathemas of the Second Council of Constantinople, No. 8

If anyone confesses that the union took place out of two natures or speaks of the one incarnate nature of God the Word and does not understand those expressions as the holy Fathers have taught, that out of the divine and human natures, when union by hypostasis took place, one Christ was formed; but from these expressions tries to introduce one nature or essence of the Godhead and manhood of Christ; let him be anathema. For in saying that the only-begotten Word was united by hypostasis personally we do not mean that there was a mutual confusion of natures, but rather we understand that the Word was united to the flesh, each nature remaining what it was. Therefore there is one Christ, God and man, of the same essence with the Father as touching his Godhead, and of the same essence with us as touching his manhood. Therefore the Church of God equally rejects and anathematizes those who divide or cut apart or who introduce confusion into the mystery of the divine dispensation of Christ.