1 You foolish Galatians! Who has bewitched you? Before your very eyes Jesus Christ was clearly portrayed as crucified. 2 I would like to learn just one thing from you: Did you receive the Spirit by observing the law, or by believing what you heard? 3 Are you so foolish? After beginning with the Spirit, are you now trying to finish by human effort? 4 Have you experienced so much in vain—if it really was in vain? 5 Does God give you his Spirit and work miracles among you by your observing the law, or by your believing what you heard? (TNIV)Something critical that many commentators miss in Galatians is the centrality of the Holy Spirit. As expected, Gordon Fee is an exception (Hays and McKnight pick up on this theme, too, to a lesser extent). Fee's discussion at one point was so helpful that I'll quote it at length,
...[A]long with many other passages throughout the corpus, this appeal to "reception of the Spirit" as evidence of entry into the Christian life demonstrates the crucial role that the Spirit plays not only in Christian conversion itself but also as the singular "identity mark" of those who belong to Christ. After all, at issue throughout is proper evidence of identity. What uniquely distinguishes God's people, marks them off as inheritors of the promises made to Abraham? The agitators are urging circumcision, probably on the basis of Gentile inclusion in the covenant with Abraham in Gen. 12:3 and 17:4-7, 12. Paul argues for the Spirit. As the question makes certain, for Paul the Spirit alone functions as the seal of divine ownership, the certain evidence that one has entered into the life of the new aeon. As such, even though Paul's expressed contrasts for his present purposes are between "hearing of faith" and "works of law," the ultimate contrast is between life under law (= slavery) and life in the Spirit (= adoption as children), as 4:1-7 makes clear and 5:13-6:10 will further amplify. The Spirit alone distinguishes God's people in the new covenant.I think that this forms a wonderful summary of what's going on in the body of Paul's argument from 3:1-6:10. What I found most helpful is that seeing the centrality of the Spirit in Paul's argument demonstrates that the letter is all about the how and what of the people of God. The Spirit is mentioned explicitly in five sections, the current one (3:1-5), in 3:14, 4:6, 4:29 and 5:16-6:10. The thing to notice is the way the Spirit is talked about in relation to us. Except for the final section the Spirit is directly linked either to our status as the people of God or is used in a relational/familial metaphor. This shows that Fee's conclusion is right on, that Galatians is about how we can tell who the people of God are and as Fee also points out, this is what ties the closing parensis to the rest of the letter, and in fact makes it integral, for if you have the Spirit than your life must show evidence of it.
Fourth, the entire argument comes aground if the appeal is not also to a reception of the Spirit that was dynamically experienced. Although Paul seldom mentions any of the visible evidences of the Spirit in contexts such as these, here is the demonstration that the experience of the Spirit in the Pauline churches was very much like that described and understood by Luke - as visibly and experientially by phenomena that gave certain evidence of the presence of the Spirit of God. Not only is this the clear point of the rest of the argument in vv. 4-5, but also such an understanding alone makes the present rhetoric possible at all. Not only so, but such an experienced reality best accounts for the way that Paul picks up the argument about life in the Spirit in 5:13-6:10. Many of the difficulties moderns have with the latter passage - and its promises - lie with the general lack of appreciation for the dynamically experienced nature of life in the Spirit in the early church (106-7).