Hence observe, That a man must be righteous before he can do any good work.
Quest. Righteous! "With what righteousness?"
Answ. With the righteousness of faith. And therefore it is said, that Abel had faith before he offered sacrifice. "By faith he offered" (Heb 11:4). Where faith is made to precede or go before the work which by faith he offered unto God.
Quest. But are not good works the righteousness of faith?
Answ. They are the fruits of faith: As here in the case of Abel; his faith produced an offering; but before he gave his offering, his faith had made him righteous; for faith respects a promise of grace, not a work of mine: Now the promise of grace, being this, that the seed of the woman, which is Christ, should destroy the power of the devil; by this Abel saw that it was Christ that should abolish sin and death by himself, and bring in "everlasting righteousness" for sinners. Thus believing, he had accepted of Christ for righteousness, which because he had done, God in truth proclaims him righteous, by accepting of his person and performances when offered.
Abel then presented his person and offering, as shrouding both, by faith, under the righteousness of Christ, which lay wrapped up in the promise; but Cain stands upon his own legs, and so presents his offering. Abel therefore is accepted, both his person and his offering, while Cain remains accursed.
Ver. 5. "But unto Cain, and to his offering, he [the Lord] had not respect. And Cain was very wroth, and his countenance fell."
Mark: As first Abel's person is accepted, and then his offering; so first Cain's person is rejected, and afterwards his offering: For God seeth not sin in his own institutions, unless they be defiled by them that worship him; and that they needs must, when persons by[18] themselves offer sacrifice to God, because then they want the righteousness of faith.
This then made the difference betwixt Abel and his brother; Abel had faith, but Cain had none. Abel's faith covered him with Jesus Christ, therefore he stood righteous in his person before God: This being so, his offering was accepted, because it was the offering of one that was righteous.
"But unto Cain, and to his offering, the Lord had not respect." Hence note, That a Christless man is a wicked man, let him be never so full of actions that be righteous; for righteous actions make not a righteous man, the man himself must first be righteous.[19]