This one thing would I learn of you
Though there were many things he could have put to them, yet he would only ask this one question, which, if rightly attended to, and honestly answered, must expose their folly, and put an end to the controversy upon this head:
received ye the Spirit by the works of the law, or by the hearing
This question supposes they had received the Spirit; that is, the Spirit of God, as a spirit of wisdom and knowledge in the revelation of Christ; as a spirit of regeneration and sanctification; as a spirit of faith and adoption; and as the earnest, seal, and pledge of their future glory. Now the apostle asks, whether they received this Spirit "by the works of the law"; meaning, either whether they could imagine, that they by their obedience to the law had merited and procured the Spirit of God; or whether they thought that the Spirit came to them, and into their hearts, through the doctrine or preaching of the law: the former could not be true, for if they could not obtain righteousness and life by the works of the law, then not the Spirit; besides, works done without the Spirit of God, are not properly good works: not the latter, for though by the law is the knowledge of sin, yet this leaves nothing but a sense of wrath and damnation in the conscience; it is the killing letter, and a ministration of condemnation and death, and not of the Spirit, and of life; this belongs to the Gospel, "or the hearing of faith"; for by "faith", is meant the Gospel, and particularly the doctrine of justification by faith in Christ's righteousness; and by "the hearing" of it, the preaching of it, the report of it, ( Isaiah 53:1 ) which, in the Hebrew text, is (wntemv) , "our hearing", that by which the Gospel is heard and understood. Now in this way the Spirit of God is received; while the Gospel is preaching he falls on them that hear it, conveys himself into their hearts, and begets them again by the word of truth: and in this way the Galatians came by the Spirit, and which is another aggravation of their folly, that they should enjoy so great an advantage by the Gospel, and yet be so easily removed from it.