Usually when I read Galatians, I just pick up on cool little verses here and there, but today I focused more on noticing Paul’s overall theme, which I think can be summarized by these verses from Chapter 5:
For freedom Christ has set us free; stand firm therefore, and do not submit again to a yoke of slavery.
2 Look: I, Paul, say to you that if you accept circumcision, Christ will be of no advantage to you. 3 I testify again to every man who accepts circumcision that he is obligated to keep the whole law. 4 You are severed from Christ, you who would be justified by the law; you have fallen away from grace. 5 For through the Spirit, by faith, we ourselves eagerly wait for the hope of righteousness. 6 For in Christ Jesus neither circumcision nor uncircumcision counts for anything, but only faith working through love.
It really seems to me that the whole book should be interpreted with this theme in mind. Paul seems to be addressing one issue in the whole book and just about every thing he says is directly related to it.
The issue of course is that some people were spreading the false idea among the church that following the Mosaic Law (ie. circumcision) was more righteous than not following the law. Paul seems pretty angry with those people, and his anger comes out all throughout this book as he continually blasts them for their falsehood.
One really interesting part is when he is discussing Sarah and Hagar (Galatians 4:21-31). It is an incredibly direct attack on the circumcision group, because it was Sarah’s child who received the covenant of circumcision, but Paul shows that those who rely on circumcision actually end up being sons of Hagar. Sarah’s true sons are those who rely on faith in Jesus Christ alone.