Reading Galatians 2 today in my endeavor to read the Bible through during the year. The problem with reading Paul's letters quickly is he gives us so much to think about.
My first thought is that his literary structure is elegant. The first story (2:1-10) shows the leaders of the Jerusalem church, the apostles, acceptance of Gentiles and Paul's message to them. It sets up a jarring contrast to the second story, where Judaizers do not accept Gentile believers and influence even Peter, one of the "pillars" of the Jerusalem church.
Now that you see this contrast, Paul gives the theological conclusion. The conclusion (2:15-21) states the doctrine of justification by faith. Justification means to be declared righteous by God. We are justified through our faith in Christ, not by our works.