Introduction
Every other letter Paul writes opens with thanksgiving. This one does not. He skips the courtesy and goes straight to alarm: 'I am astonished that you are so quickly deserting the one who called you.'
Something had come into the Galatian churches after he left — teaching that added requirements to faith in Christ. It sounded like a small refinement. Paul treats it as a different religion.
The main point: the gospel is not a foundation you build additions onto. Add to it and you have replaced it.
I. No Other Gospel (Galatians 1:1-10)
Paul's urgency shows in the first sentence. He is an apostle 'sent not from men nor by a man, but by Jesus Christ and God the Father.' The credentials matter because his message is being questioned.
That is a startling thing to say, and Paul says it twice. He is not defending his authorship. He is saying that his own credentials would not save a false message, and neither would an angel's.
II. Where the Message Came From (Galatians 1:11-24; Acts 9:1-19)
Then his story, told to settle one question: is this gospel something Paul invented or inherited from other men?
And the detail he wants noticed: the churches in Judea 'only heard the report, The man who formerly persecuted us is now preaching the faith he once tried to destroy. And they praised God because of me.' The evidence is a changed life, and it was God who was praised for it.
III. The Gospel Confirmed, Not Corrected (Galatians 2:1-10)
Fourteen years later Paul goes to Jerusalem and lays out his message before the leaders there. The outcome is the point of the passage.
And one request: 'that we should continue to remember the poor, the very thing I had been eager to do all along.' A gospel of pure grace produced not laziness but generosity, and everyone in that room assumed it would.
Conclusion & Appeal
The Galatian error is alive and well, though it rarely uses the old vocabulary. It shows up as a quiet conviction that God accepts you and then keeps a running tally of whether you are holding up your end.
That is not a smaller version of the gospel. It is a different one, and it will exhaust you, because a righteousness you maintain is a righteousness you can lose.
So ask yourself this week: what am I doing to keep God's approval that Christ has already secured? Write it down. Then read the first two chapters of this letter again and notice how hard Paul fought to keep you from having to do it.