1 John 3:8

8. He that committeth sin is of the devil—in contrast to "He that doeth righteousness," 1 John 3:7. He is a son of the devil (1 John 3:10; John 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.