Romans 5:20

Moreover, the law entered
By "the law" is meant, not the law of nature, much less the law of sin; rather the ceremonial law, which came in over and above the moral law; it entered but for a time; by which sin abounded, and appeared very sinful; and through it the grace of God much more abounded, in the sacrifice of Christ prefigured by it: but the moral law, as it came by Moses, is here intended; which entered with great pomp and solemnity on Mount Sinai; and intervened, or came between Adam's sin and Christ's sacrifice; and also came in besides, or over and above the promise of life by Christ; and may moreover be said to enter into the conscience of a sinner, with the power and energy of the Spirit of God: and the end of its entrance is,

that the offence might abound;
meaning either the sin of Adam, he had been speaking of under that name, that that itself, and the imputation of it to his posterity, and also the pollution of human nature by it, together with all the aggravating circumstances of it, might appear more manifest; or sin in general, any and all actual transgressions, which abound through the law's discovering the evil nature of them, and so taking away all excuse, or pretext of ignorance: by prohibiting them, whereby the corrupt nature of man becomes more eager after them; and by accusing, threatening, terrifying, and condemning, on account of them: one view of the apostle in this, doubtless, is to show, that there can be no justification by the law:

but where sin abounded, grace did much more abound:
sin has abounded in human nature, in all the individuals of it; and grace has superabounded in the same nature, being assumed by the Son of God, and united to him, who has appeared in it "full of grace and truth", ( John 1:14 ) : sin has abounded in all the powers and faculties of the soul, in the understanding, will, and affections, of an unregenerate man; but in regeneration, the grace of God much more abounds in the same powers and faculties, enlightening the understanding, subduing the will, and influencing the affections with love to divine things: sin abounded in the Gentile world, before the preaching of the Gospel in it; but afterwards grace did superabound in the conversion of multitudes in it from idols, to serve the living God; and where sin has abounded in particular persons to a very great height, grace has exceeded it, as in Manasseh, Mary Magdalene, Saul, and others.