Everyone who sins also commits lawlessness. Sin is lawlessness.
For sin is the transgression of the law - That is, all sin involves this as a consequence that it is a violation of the law. The object of the apostle is not so much to define sin, as to deter from its commission by stating what is its essential nature - though he has in fact given the best definition of it that could be given. The essential idea is, that God has given a law to people to regulate their conduct, and that whatever is a departure from that law in any way is held to be sin. The law measures our duty, and measures therefore the degree of guilt when it is not obeyed. The law determines what is right in all cases, and, of course, what is wrong when it is not complied with. The law is the expression of what is the will of God as to what we shall do; and when that is not done, there is sin. The law determines what we shall love or not love; when our passions and appetites shall be bounded and restrained, and to what extent they may be indulged; what shall be our motives and aims in living; how we shall act toward God and toward people; and whenever, in any of these respects, its requirements are not complied with, there is sin.