Paul has already warned the Galatians twice in chapter 1 that if anyone is preaching a gospel contrary to the one he preached, they are to be anathema, accursed, considered outside the faith that was once-and-for-all
delivered to the saints. At the end of chapter 2, Paul begins to get a little more specific about the problem that these churches are dealing with: their doctrine of justification. At the end of Galatians 2:16, Paul said “by works of the law no one will be justified.”