Letter to Theodosius

1We confess, then, that the only-begotten Son of God is perfect God, consubstantial with the Father in divinity and consubstantial with us in humanity. A union of natures has occurred, and from this we confess one Christ, one Son, one Lord. If it seems good, let us take as an example the composition by which we ourselves are human. We are composed of soul and body, and we see two natures, one of the body and another of the soul, yet the one human being from both in union does not make us think of two human beings because he is composed from two natures, but one human being. For if we do away with the fact that the one and only Christ is from two different natures, our opponents will say: if the whole is one nature, how did he become human, or what flesh did he take to himself? As for those who say that a mixture or confusion or blending of God the Word with the flesh occurred, the catholic and apostolic church anathematizes them.