Indwelling sin is compared to a person, a living person, called “the old man,” with his faculties and properties, his wisdom, craft, subtlety, strength; this, says the apostle, must be killed, put to death, mortified—that is, have its power, life, vigor, and strength to produce its effects taken away by the Spirit. It is, indeed, meritoriously, and by way of example, utterly mortified and slain by the cross of Christ; and the “old man” is thence said to be “crucified with Christ” (Rom. 6:6).
“If ye by the Spirit do mortifie the deeds of the flesh, ye shall live” (Rom. 8:13)
The Duty: Mortify Your Deeds
The duty itself, “Mortify the deeds of the body,” is next to be remarked upon. Three things are here to be inquired into:
(1) What is meant by the body?
(2) What by the deeds of the body?
(3) What by mortifying of them?
(1) “The body” in the close of the verse is the same with “the flesh” in the beginning: “If ye live after the flesh ye shall dye,” but if ye “mortifie the deeds of the body”—that is, of the flesh. It is that which the apostle has all along discoursed of under the name of “the flesh,” which is evident from the prosecution1 of the antithesis between the Spirit and the flesh, before and after. “The body,” then, here is taken for that corruption and depravity of our natures whereof the body, in a great part, is the seat and instrument, the very members of the body being made servants unto unrighteousness thereby (Rom. 6:19). It is indwelling sin, the corrupted flesh or lust, that is intended. Many reasons might be given of this metonymical expression2that I shall not now insist on. The “body” here is the same with παλαιὸς ἄνθρωπος and σῶμα τῆς ἁμαρτίας, the “old man” and the “body of sin” (Rom. 6:6); or it may synecdochically3 express the whole person considered as corrupted, and the seat of lusts and distempered affections.
(2) The deeds of the body. The word is πράξεις,4 which, indeed, denotes the outward actions chiefly, “the works of the flesh,” as they are called, τὰ ἔργα τῆς σαρκὸς (Gal. 5:19); which are there said to be “manifest” and are enumerated. Now, though the outward deeds are here only expressed, yet the inward and next causes are chiefly intended; the “axe is to be laid to the root of the tree”5—the deeds of the flesh are to be mortified in their causes, from whence they spring. The apostle calls them deeds, as that which every lust tends unto; though they do but conceive and prove abortive, they aim to bring forth a perfect sin.