1 John 3:4

Whosoever committeth sin
This, in connection with what follows, is true of any sin, great or small, but here designs a course of sinning, a wilful, obstinate, persisting in sin:

transgresseth also the law;
not of man, unless the law of men is founded on, and agrees with the law of God, for sometimes to transgress the laws of men is no sin, and to obey them would be criminal; but the law of God, and that not the ceremonial law, which was now abolished, and therefore to neglect it, or go contrary to it, was not sinful; but the moral law, and every precept of it, which regards love to God or to our neighbour, and which may be transgressed in thought, word, and deed; and he that committeth sin transgresses it in one or all of these ways, of which the law accuses and convicts, and for it pronounces guilty before God, and curses and condemns; and this therefore is an argument against sinning, because it is against the law of God, which is holy, just, and good, and contains the good and acceptable, and perfect will of God, which is agreeable to his nature and perfections; so that sin is ultimately against God himself:

for sin is a transgression of the law;
and whatever is a transgression of the law is sin; the law requires a conformity of nature and actions to it, and where there is a want of either, it is a breach of it; it is concerned with the will and affections, the inclinations and desires of the mind, as well as the outward actions of life; concupiscence or lust is a violation of the law, as well as actual sin; and especially a course of sinning both in heart, lip, and life, is a continued transgression of it, and exposes to its curse and condemnation, and to the wrath of God; and is inconsistent with a true hope of being the sons and heirs of God: but then the transgression of what is not the law of God, whether the traditions of the elders among the Jews, or the ordinances of men among Papists, Pagans, and Turks, or any other, is no sin, nor should affect the consciences of men.