John Chrysostom

He does not say, let not the flesh live or act, but, "let not sin reign," for He came not to destroy our nature, but to set our free choice aright. Then to show that it is not through any force or necessity that we are held down by iniquity, but willingly, he does not say, let it not tyrannize, a word that would imply a necessity, but let it not reign. For it is absurd for those who are being conducted to the kingdom of heaven to have sin empress over them, and for those who are called to reign with Christ to choose to be the captives of sin, as though one should hurl the diadem from off his head, and choose to be the slave of a frantic woman, who came begging, and was clothed in rags. Next since it was a heavy task to get the upper hand of sin, see how he shows it to be even easy, and how he allays the labor by saying, "in your mortal body." For this shows that the struggles were but for a time, and would soon bring themselves to a close. At the same time he reminds us of our former evil plight, and of the root of death, as it was from this that, contrary even to its beginning, it became mortal. Yet it is possible even for one with a mortal body not to sin. Do you see the abundancy of Christ's grace? For Adam, though as yet he had not a mortal body, fell. But thou, who hast received one even subject to death, canst be crowned. How then, is it that "sin reigns?" he says. It is not from any power of its own, but from thy listlessness. Wherefore after saying, "let it not reign," he also points out the mode of this reigning, by going on to say "that ye should obey it in the lusts thereof." For it is not honor to concede to it (i.e. to the body) all things at will, nay, it is slavery in the extreme, and the height of dishonor; for when it doth what it listeth, then is it bereft of all liberties; but when it is put under restraints, then it best keeps its own proper rank.