3:5-11 It is our duty to mortify our members which incline to the things of the world. Mortify them, kill them, suppress them, as weeds or vermin which spread and destroy all about them. Continual opposition must be made to all corrupt workings, and no provision made for carnal indulgences. Occasions of sin must be avoided: the lusts of the flesh, and the love of the world; and covetousness, which is idolatry; love of present good, and of outward enjoyments. It is necessary to mortify sins, because if we do not kill them, they will kill us. The gospel changes the higher as well as the lower powers of the soul, and supports the rule of right reason and conscience, over appetite and passion. There is now no difference from country, or conditions and circumstances of life. It is the duty of every one to be holy, because Christ is a Christian's All, his only Lord and Saviour, and all his hope and happiness.
10. the new man—(See on Eph 4:23). Here (neon) the Greek, means "the recently-put-on nature"; that lately received at regeneration (see on Eph 4:23, 24).
which is renewed—Greek, "which is being renewed" (anakainottmenou); namely, its development into a perfectly renewed nature is continually progressing to completion.
in knowledge—rather as the Greek, "unto perfect knowledge" (see on Col 1:6; Col 1:9, 10). Perfect knowledge of God excludes all sin (Joh 17:3).
after the image of him that created him—namely, of God that created the new man (Eph 2:10; 4:24). The new creation is analogous to the first creation (2Co 4:6). As man was then made in the image of God naturally, so now spiritually. But the image of God formed in us by the Spirit of God, is as much more glorious than that borne by Adam, as the Second Man, the Lord from heaven, is more glorious than the first man. Ge 1:26, "Let us make man in our image, after our likeness." The "image" is claimed for man, 1Co 11:7; the "likeness," Jas 3:9. Origen [On First Principles, 3:6] taught, the image was something in which all were created, and which continued to man after the fall (Ge 9:6). The likeness was something towards which man was created, that he might strive after it and attain it. Trench thinks God in the double statement (Ge 1:26), contemplates both man's first creation and his being "renewed in knowledge after the image of Him that created Him."