1 John 3:4

Everyone that doeth sin doeth also lawlessness; and sin is lawlessness.

And sin is lawlessness ... Here the KJV is far better: "Sin is the transgression of the law." And what law is in view? "He is not thinking of the law of Moses."[14] Nor can we agree with Blaney that, "transgression of the law of love"[15] alone is meant. "It means the law of God in the fullest sense, not Moses' law, but transgression of the will of God."[16] Particularly, it is "the law of Christ" which sin transgresses; and that may not be limited to any classification of Jesus' commandments, but includes "all things whatsoever I have commanded you" (Matthew 28:18-10). Inherent in this is the epic truth that the grace of God has not abolished sin. The proposition that "we are not under law but under grace," while true enough as related to the law of Moses, does not relax any of the law of Christ (See more on this in my Commentary on Galatians, Ephesians, Philippians, and Colossians, pp. 115,117).

[14] W. N. Sinclair, op. cit., p. 483.

[15] Harvey J. S. Blaney, op. cit., p. 378.

[16] A. Plummer, op. cit., p. 71.