Disputed, between about AD 48 and 55, depending on which Galatia he means.
What it is
A furious letter, the only one with no thanksgiving at the start, arguing that Gentile believers need not become Jews first.
What to watch for
He tells the story of falling out with Peter to their faces, in writing, as evidence.
I have been crucified with Christ, and I no longer live, but Christ lives in me. The life I live in the body, I live by faith in the Son of God, who loved me and gave Himself up for me.Galatians 2:20