1 John 3:4

Whosoever. John states the opposite case with enough variation to make it add to, as well as confirm, his previous statement: all having the hope purify themselves; all doing the sin, do also lawlessness.

Sin. Greek hamartia, “a failing to hit the mark,” “a wrong deed,” “a sin,” from hamartanō, “to miss the mark,” “to err,” “to do wrong,” “to go wrong,” “to sin,” and is a word used in the Bible for the act of wandering from the law of God, of violating moral law. Specifically, hamartia is a violation of divinely given moral law. The word can also refer to the principle and power that causes one to commit sin (see on Rom. 5:12), but here John is obviously referring to the evil deed itself.

The Greek reads literally, “the sin.” It does not appear, however, that John is referring to any particular sin, neither does the context identify “the sin,” but the use of the definite article suggests that the writer is speaking of all types of sin as one sin, the sin that causes separation between God and man (cf. Isa. 59:2).

Transgresseth also the law. Literally, “also the lawlessness doeth.” The KJV reading is a rather free rendering of the Greek. “Lawlessness” is the translation of the Greek anomia (“lack of conformity with law,” “lawlessness”) derived from a-, “without,” and nomos, “law” (see on Matt. 7:23; Rom. 6:19; 2 Thess. 2:3, 7). By linking anomia with hamartia the apostle emphasizes the close connection between sin and lawlessness. With his customary clarity he makes this doubly clear by restating the fact in the phrase that follows.

For sin is the transgression of the law. Literally, “and the sin is the lawlessness.”

The use of the article with each noun makes them interchangeable: all sin is lawlessness, and all lawlessness is sin. In his usual simple and penetrating way John lays bare the true character of sin. He states that sin is disregard of the law, that is, the law of God. For definitions of “law” see on Prov. 3:1; Matt. 5:17; Rom 2:12; 3:19. God formulated laws to guide men, to enable them to enjoy life fully, to save them from evil, and to preserve them for good (see on Ex. 20:1).

The law of God is a transcript of the character of God. Jesus came to reveal to men the character of His Father. He is therefore the law amplified and demonstrated. If men wish to order their lives in harmony with the law of God, they must look to Jesus and copy His life. The law may be briefly summarized in the following words, “be like God,” or “be like Jesus.” The transformation of men’s characters after the divine similitude is the great purpose of the plan of salvation. The law reveals the character of God and of Christ; the plan of salvation provides enabling grace for the attainment of every virtue.