I John 3:8

He that committeth sin is of the devil--in contrast to "He that doeth righteousness," Jo1 3:7. He is a son of the devil (Jo1 3:10; Joh 8:44). John does not, however, say, "born of the devil." as he does "born of God," for "the devil begets none, nor does he create any; but whoever imitates the devil becomes a child of the devil by imitating him, not by proper birth" [AUGUSTINE, Ten Homilies on the First Epistle of John, Homily 4.10]. From the devil there is not generation, but corruption [BENGEL]. sinneth from the beginning--from the time that any began to sin [ALFORD]: from the time that he became what he is, the devil. He seems to have kept his first estate only a very short time after his creation [BENGEL]. Since the fall of man [at the beginning of our world] the devil is (ever) sinning (this is the force of "sinneth"; he has sinned from the beginning, is the cause of all sins, and still goes on sinning; present). As the author of sin, and prince of this world, he has never ceased to seduce man to sin [LUECKE]. destroy--break up and do away with; bruising and crushing the serpent's head. works of the devil--sin, and all its awful consequences. John argues, Christians cannot do that which Christ came to destroy.

The apostle here magnifies the love of God in our adoption (Jo1 3:1, Jo1 3:2). He thereupon argues for holiness (Jo1 3:3), and against sin (v. 4-19). He presses brotherly love (Jo1 3:11-18). How to assure our hearts before God (Jo1 3:19-22). The precept of faith (Jo1 3:23). And the good of obedience (Jo1 3:24).

3:8 destroy: This does not mean “to annihilate” but “to break down” (see Eph 2:14), “to undo,” or “to render ineffective.” Christ did not obliterate Satan; he came to undo the works of the devil by freeing people from sin and its awful consequences.