Paul spends a lot of time demonstrating the incompatibility of Christ and justification by works. If the appeal did not come from people claiming to serve Christ, that sort of argumentation is unnecessary.
I am shocked that you are so quickly deserting the one calling you in the grace of Christ [in order to follow] a different gospel. It's not another [gospel]; rather, some people are disturbing you and trying to distort the gospel of Christ. —1:6-7
- The error is still being presented as the Gospel.
- This Gospel must purport to be the same Gospel, or it would not be a distortion; it would be something completely different.
1:8-2:14: He attempts to authenticate his Gospel by proclaiming it comes directly from Christ. If his opponents had no interest in Christ, he wouldn't go to such length to show it was in accord with the message of the other apostles, etc.
2:15-21: Summed up by verse 21:
So I do not reject the grace of God: for if righteousness is through the law, then there was no reason for Christ to die!
Once again, if his opponents are already saying Forget about Christ, then this is not a useful way to argue.
[3-4 not as crucial to my argument.]
Listen. I, Paul, tell you that if you would be circumcised, Christ will profit you nothing. —5:2
This is his introduction to the argument of 5:2-12, and once again, he is working hard to show the incompatibility of Christ with something else. If Christ is already being thrown out, this argument is not helpful.
[5:13-6:11 is not so relevant to my argument.]
For in Christ Jesus neither being circumcised nor being uncircumcised count for anything, but being a new creation. —6:15
In the last paragraph he takes a final shot at the false teachers. This statement also makes the most sense in opposition to people who are saying "Jesus+something else".
The Logic of Debates
Identify three players: P (one side—Paul), M (middle of the debate—Galatians), F (other side—false teachers).
- If P holds position A (Christ), and F holds non-A, and M is caught in the crossfire, P will argue A (potentially by arguing "not non-A"), regardless of whether his argument is addressed to M or F.
- If P holds position A, and F holds position B (circumcision etc.), and M is in a position of wanting to affirm A and B, P must:
- argue that B implies non-A if he wants to address M
- argue non-B on some other basis if he wants to address F
Now, if Paul's opponents are saying to cast off Christ, you get the first situation, where Paul will argue against casting off Christ (not non-A). However, the argument of the book of Galatians is of the second type, and the book is addressed to M (Christians, who have already affirmed A), so he must argue the incompatibility of B and A, which we find that he in fact does.
Is it possible that those who wanted to bring back the law were doing it to please certain non-Christian Jews? Yes; it even seems likely. However, the false teachers Paul is specifically opposing cannot have been trying to convince the Galatians to throw off Christ, or Paul's argument misfires.