Everyone who sins also commits lawlessness. Sin is lawlessness.
for sin is the transgression of the law: Solomon says that "the thought of foolishness is sin" (Proverbs 24:9); Paul says that "whatsoever is not of faith is sin" (Romans 14:23); James says, "Therefore to him that knoweth to do good, and doeth it not, to him it is sin" (James 4:17); and John, in the latter part of this epistle, says, "All unrighteousness is sin" (1 John 5:17). Whether John intends to give a definition of sin or not is immaterial; he does give us one. "Sin is lawlessness; lawlessness is sin." The sentence can be read backwards and forwards and teach the same truth. Wuest says that the "Greek construction makes sin and lawlessness identical" (Wuest, I John 147). When one sins, he is lawless; when one is lawless, he sins. Sin is no trivial matter: it separates from God and damns the soul. Lawlessness is no small matter either; it places one in opposition to the Lawgiver Who will deliver the lawbreaker to receive the reward of unrighteousness. God has a law, called the "perfect law of liberty" (James 1:25), which must be studiously respected by all of God’s people. "So speak ye, and so do, as they that shall be judged by the law of liberty" (James 2:12). John, doubtless, has the Cerinthian Gnostics in mind as he writes these words. They considered themselves as the spiritually elite who lived above the law and owed no allegiance to it. John says, "You are lawless sinners."