This is a response to Mason's post from earlier today.
Mase,
Kruse deals with this in his book, Paul, the Law, and Justification. He gives three possible explanations, only two of which I think are worth considering. Here is the pertinent section from the book:
Paul and Cephas agreed about rejecting legalism (i.e. that fulfilling the demands of the law was not necessary for justification), but they disagreed on the matter of nomism (i.e. that those who had been justified by faith were required to observe the demands of the law as part of their ongoing Christian obedience). Paul expresses this disagreement in the question: 'But if, in our effort to be justified in Christ, we ourselves have been found to be sinners, is Christ then a servant of sin? Certainly not!' (2:17). This question has been interpreted in a number of ways.
First, it has been interpreted to mean that when Jewish Christians, depending upon Christ for justification, ceased to observe all that the law demanded (e.g. by eating with Gentile believers), they found themselves branded as sinners by the law, and thus no better than Gentiles (cf. 2:15). Thus it could be said that Christ was a servant of sin in so far as it was faith in him which turned them into transgressors. To such a preposterous suggestion Paul responds, 'Certainly not!' He then goes on to explain that it is only when Jewish believers re-erect for themselves the jurisdiction of the law that they become transgressors of it (2:18). But in fact Jewish believers need not fear being branded sinners by the law, because in Christ they have died to any relationship to the law (2:19).
Second, the passage has been interpreted in the light of the supposed libertine tendencies of the Galatians themselves (cf. 5:13-26). In this case verses 17-20 would be Paul's response to assertions that it was his law-free gospel which had allowed the Galatian believers to indulge in a licentious lifestyle, and so his Christ was a servant of sin. Paul's response would then be to acknowledge that while we (a rhetorical softening by identifying himself with those whom he seeks to correct) were seeking to be justified in Christ, we were found (sadly) to be guilty of a sinful lifestyle. But does this mean that Christ is a servant of sin? God forbid! Longenecker, who espouses this view, expresses it as follows: 'For, Paul insists, to go back to the law (as a Christian) after having finished with the law (for both acceptance before God and living a life pleasing to him) is what really makes one a law breaker-which, of course, sounds paradoxical, but is what happens if one rejects legalism but still espouses nomism.'
I don't know if that helped at all, or just muddied the waters, but there it is either way :-) I prefer the first explanation myself, but I am by no means an expert on the passage. Hopefully Chad will chime in, as I think he has a good grasp on the flow of Paul's argument here. You might also find something JT posted a while back as helpful.
gh
