In the first place, that the righteousness by which we are justified before God is not of works, is not only asserted, but proved. The apostle’s first argument on this point is derived from the consideration, that the law demands a perfect righteousness. If the law was satisfied by an imperfect obedience, or by a routine of external duties, or by any service which men are competent to render, then indeed justification would be by works. But since it demands perfect obedience, justification by works is, for sinners, absolutely impossible. It is thus the apostle reasons, ‘As many as are of the works of the law are under the curse: for it is written, Cursed is every one that continueth not in all things which are written in the book of the law to do them’ (Gal. 3:10). As the law pronounces its curse upon every man who continues not to do all that it commands, and as no man can pretend to this perfect obedience, it follows that all who look to the law for justification must be condemned. To the same effect, in a following verse, he says, ‘The law is not of faith: but, The man that doeth them shall live in them.’ That is, the law is not satisfied by any single grace, or imperfect obedience. It knows, and can know no other ground of justification than complete compliance with its demands. Hence, in the same chapter, Paul says, ‘If there had been a law given which could have given life, verily righteousness should have been by the law.’ Could the law pronounce righteous, and thus give a title to the promised life to those who had broken its commands, there would have been no necessity of any other provision for the salvation of men; but as the law cannot thus lower its demands, justification by the law is impossible. The same truth is taught in a different form, when it is said, ‘If righteousness come by the law, then Christ is dead in vain’ (Gal. 2:21). There would have been no necessity for the death of Christ, if it had been possible to satisfy the law by the imperfect obedience which we can render. Paul therefore warns all those who look to works for justification, that they are debtors to do the whole law (Gal. 5:3). It knows no compromise; it cannot demand less than what is right, and perfect obedience is right , and therefore its only language is as before, ‘Cursed is every one that continueth not in all things which are written in the book of the law to do them’ (Gal. 3:10); and, ‘The man which doeth those things shall live by them’ (Rom. 10:5). Every man, therefore, who expects justification by works, must see to it, not that he is better than other men, or that he is very exact and does many things, or that he fasts twice in the week, and gives tithes of all he possesses, but that he is SINLESS.
Charles Hodge, The Way of Life (East Peoria: Banner of Truth, repr. 2020), 109–10. Emphasis original. HT: Inwoo Lee.