(2) This only.--The Apostle considers a single argument enough. He will only place the present conduct of the Galatians in contrast with their past, and ask how they can possibly reconcile the two.

Received ye the Spirit.--The reference is to those spiritual gifts, described more fully in 1 Corinthians 12, 14--the gift of prophecy, the gift of tongues, the interpretation of tongues, the discerning of spirits, gifts of healing, &c.--which attended the first preaching of the gospel, and were poured out upon the first converts in a manner and degree since unknown. The Galatians, it seems, had had a share in this outpouring, like the other churches, though their fickleness prevented them from reaping the full benefit from it. But a spiritual effect, such as this outpouring was, could only have a spiritual cause; it could not come from a mechanical performance of legal obligations.

By the works of the law.--By works done in obedience to the Law. There is a certain emphasis on both words, for the main point in the contrast which the Apostle is drawing is between the Law, on the one hand, and faith, on the other. Still, faith is as much opposed to works (i.e., a spirit of literal and mechanical obedience) as it is to Law, and excludes both at once. It is to be noted, however, that the works here meant are those done, in a Judaising sense, as themselves the direct means of salvation--not Christian works, the natural product and outcome of faith.

By the hearing of faith.--These words correspond very nearly to a phrase which we should perhaps use more naturally: by the preaching of faith--i.e., by that preaching or hearing (hearing on the part of the recipients, preaching on that of the missionary Apostles) which has for its subject faith. What the Apostle had taught the Galatians on his first coming among them was not any system of laborious observances, but the duty of faith. They at first responded to his teaching: and in answer to their enthusiastic impulse of adhesion to Christ the gifts of the Spirit were abundantly shed upon them. Now all this had ceased. For the use of the word translated "hearing," see the Note on Romans 10:16.

Verse 2. - This only would I learn of you (τοῦτο μόνον θέλω μαθεῖν ἀφ ὑμῶν); this only would I learn from you. I need ask for nothing more to show that the Law is nothing to you, than that you should tell me this. Received ye the Spirit by the works of the Law? (ἐξ ἔργων νόμου τὸ Πνεῦμα ἐλάβετε;); was it in consequence of works of the Law that ye received the Spirit? I came amongst you as an apostle, preaching the gospel, and upon your baptism laying my hands upon you; and the Holy Spirit came down upon you, proving the reality of his presence both by signs and miracles and powers, and also by the love, joy, and peace with which your hearts were filled; sealing at once the truth of my doctrine and your own position individually as recognized heirs of the kingdom of God. You remember that time. Well, how was it then? Had there a word been then spoken touching meats or drinks, or washings of purification (besides your baptism into Christ), or circumcision, or care of ceremonial cleanness? Had you attended to any one point whatever of Levitical ordinance? Had either you or I cast one thought in that direction? The "works of the Law" here referred to must still be works of ceremonial performance, not those of moral obedience; for repentance, the practical breaking off from sin, the surrender of the soul to God and to Christ in faith and loyal obedience, the outward assuming of the character of God's servants, the purpose and inchoate performance of works meet for repentance, - these dotings of compliance with the moral Law were there. The gift of the Spirit was evidenced by charisms plainly supernatural; but it comprised more than the bestowment of these. Or by the hearing of faith? (ἤ ἐξ ἀκοῆς πίστεως;); or was it in consequence of the hearing of faith? The noun ἀκοὴ denotes sometimes (what is heard) "report," "rumour," as Matthew 4:24; Matthew 24:6; Romans 10:16, 17; sometimes, especially in the plural, the organs or sense of hearing, as Mark 7:35; Luke 7:1; Acts 17:20; Hebrews 5:11; 2 Timothy 4:3, 4; sometimes the act of hearing, as Matthew 13:14; 1 Samuel 15:22 (Septuagint). The last appears more suitable here than the first taken (as some take it) as describing the doctrine or message which they heard respecting faith; standing as ἀκοὴ does in contrast to "works" which would have been an acting of theirs, this likewise was most probably meant by the apostle subjectively of something appearing on their own part. "Were you not at once received into the kingdom of God and filled with joy in the Holy Spirit, immediately upon your believing acceptance of the gospel message?" With exquisite propriety, as Bengel observes, is hereby marked the nature of faith, not working, but receiving. This agrees also best with the illustration which in ver. 6 the apostle gives of the phrase as introduced by him again in ver. 5.

Matthew Henry's Concise Commentary

3:1-5 Several things made the folly of the Galatian Christians worse. They had the doctrine of the cross preached, and the Lord's supper administered among them, in both which Christ crucified, and the nature of his sufferings, had been fully and clearly set forth. Had they been made partakers of the Holy Spirit, by the ministration of the law, or on account of any works done by them in obedience thereto? Was it not by their hearing and embracing the doctrine of faith in Christ alone for justification? Which of these had God owned with tokens of his favour and acceptance? It was not by the first, but the last. And those must be very unwise, who suffer themselves to be turned away from the ministry and doctrine which have been blessed to their spiritual advantage. Alas, that men should turn from the all-important doctrine of Christ crucified, to listen to useless distinctions, mere moral preaching, or wild fancies! The god of this world, by various men and means, has blinded men's eyes, lest they should learn to trust in a crucified Saviour. We may boldly demand where the fruits of the Holy Spirit are most evidently brought forth? whether among those who preach justification by the works of the law, or those who preach the doctrine of faith? Assuredly among the latter.

Gill's Exposition of the Entire Bible

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 of faith? 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 "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.

OpenBible.com