Paul's letter to the Galations

In class last week we talked about Pauls letter to the Galations. Dr. Holzapfel said that this epistle contains Paul's sharpest rebukes! This is pretty obvious when you look at the language he uses at the beginning of chapter 3: "O foolish Galatians, who hath bewitched you, that ye should not obey the truth, before whose eyes Jesus Christ hath been evidently set forth, crucified among you?"
So why was Paul so angry? The Galatians had accepted the Gospel of Jesus Christ which Paul taught them. However, after Paul left, other Jews came up from Jerusalem and started teaching the people. In essence, they taught that everything Paul said was good and correct, but just not sufficient. They taught that the Galatian converts needed to be circumcized as well as being baptized in Jesus' name. The Galatian saints heeded their teachings, and accepted these practices from the Law of Moses.
When Paul finally got word of this, he was furious. But why? Was it because he thought the Law of Moses was evil? Was he against people accepting these Jewish sentimens? Probably not. Paul himself had been a Pharisee—one of the strictest orders among the Jews—so he had lived the Law of Moses himself very strictly throughout his entire life. Later (assuming Dr. H's view that the Epistle to the Galations was actually written before the Jerusalem conference) Paul would openly censure Peter for being hypocritical in following the Law of Moses around the Jews but not the Gentiles. Was Paul just very opinionated on this point of doctrine, so he lashed out when someone disagreed with him? He probably had reasoning behind this.
Paul taught that salvation was in Jesus, not in the Law. When he saw the Galation saints accepting the teaching that they needed circumcision, and even worse, the bretheren from Jerusalem teaching this doctrine, he was abhorred. What they were teaching when the said what the Galations had done was not sufficient was actually saying that Jesus and his Atonement were not sufficient. They were teaching that baptism and faith in Christ were not sufficient for salvation, but that you needed to follow the Law of Moses. The teaching of that idea would most definitly have caused a fierce reaction from Paul. How can you teach that Jesus is not sufficient for salvation?! So, it doesn't really matter whether or not you're circumcized, or whether or not you eat pork. But if you think that the Gospel of Jesus Christ is insufficient for salvation, then that's the problem.