John Chrysostom — on Rom 1:1 (Homily on Romans 1)

“"Paul, a servant of Jesus Christ." Why did God change his name, and call him Paul who was Saul? It was, that he might not even in this respect come short of the Apostles, but that that preëminence which the chief of the Disciples had, he might also acquire; and have whereon to ground a closer union with them. And he calls himself, the servant of Christ, yet not merely this; for there be many sorts of servitude. One owing to the Creation, according to which it says, "for all are Thy servants"; and according to which it says, "Nebuchadnezzar, My servant", for the work is the servant of Him which made it. Another kind is that from the faith, of which it saith, "But God be thanked that ye were the servants of sin, but ye have obeyed from a pure heart that form of doctrine which was delivered unto you: being then made free from sin, ye became the servants of righteousness." Another is that from civil subjection, after which it saith, "Moses my servant is dead"; and indeed all the Jews were servants, but Moses in a special way as shining most brightly in the community. Since then, in all the forms of the marvellous servitude, Paul was a servant, this he puts in the room of the greatest title of dignity, saying, "a servant of Jesus Christ." And the Names appertaining to the dispensation he sets forth, going on upwards from the lowest. For with the Name Jesus, did the Angel come from Heaven when He was conceived of the Virgin, and Christ He is called from being anointed, which also itself belonged to the flesh. And with what oil, it may be asked, was He anointed? It was not with oil that He was anointed, but with the Spirit. And Scripture has instances of calling such "Christs": inasmuch as the Spirit is the chief point in the unction, and that for which the oil is used. And where does it call those "Christs" who are not anointed with oil? "Touch not," it says, "Mine anointed, and do My prophets no harm", but at that time the institution of anointing with oil did not yet even exist.”