Paul ends his testimonial narrative with an encounter he had with Peter, when he had to call him out on hypocrisy (not heresy). We know from Acts 10 that Peter was fully aware that Gentiles did not have to become Jews first in order to become Christians, but he was “separating himself” from Gentile Christians to cater to the Judaizers. Paul’s summary statement against this hypocrisy is in verse 14.
This serves as the segue into Paul’s second major topic: the true gospel of Christ. Christ is the great equalizer; believing in Christ, and receiving faith from him is how we are justified – made righteous before God. The Law of Moses, however, which the Judaizers were forcing onto Gentile Christians, does not have the power to justify anyone. This argument will be explained in greater detail in chapter 3.
What may be the high point in this passage is verse 20, when Paul writes that he has been crucified with Christ. If the Law kills, then it makes sense that he (and all of us) need to die before receiving life in Christ. As Paul explains, this giving of life is exactly why Christ had to come and die. And the Law was powerless to do this by itself.