John Damascene

He who has been born first is firstborn, whether he is the only child or has preceded other brothers. So, if the Son of God were called “firstborn” without being called “onlybegotten,” then we should understand him to be firstborn of creatures as being a creature. Since, however, he is called both firstborn and onlybegotten, we must maintain both of these as applying to him. Thus, we say that he is “the firstborn of every creature,” since he is from God, and creation is also from God…. For this very reason, that he shared flesh and blood along with us and then, also, that we were made sons of God through him by being adopted through baptism. He who is by nature Son of God has become firstborn among us who have by adoption and grace become sons of God and are accounted as his brothers.

For, although he was impassible, he became subject to the experience of human passions and was made minister of our salvation. Now, they who say that he is a servant divide the one Christ into two, just as Nestorius did. But we say that he is Lord and Master of all creation, the one Christ, the same being at once God and man, and that he knows all things, “for in him are hid all the treasures of wisdom and knowledge.”