But now, months after the Galatians received the gospel Paul preached to them, in Paul’s absence false teachers have showed up on the scene, teaching the Galatians a distorted gospel of salvation by works. Their message was that these non-Jewish Galatians really needed to become a Jews first and then maybe they could be saved by Jesus.
These troublemakers were confusing the Galatians, causing them to turn away from the true gospel. They were also bad mouthing the Apostle Paul. Paul’s misleading you. Paul’s started out working under the supervision of the apostles in Jerusalem, but now he’s gone rogue. He’s not a real apostle, he’s not legit, and you’d be better off listening to us than to Paul.
Galatians chapter 1 is Paul’s response to the challenge against his authority. It’s a response motivated by Paul’s commitment to the truth and by his love for the Galatians.