Here's one way to translate Galatians 1:8:
If anyone brings you another gospel, let him be damned.
That verse captures the heart and spirit of Galatians. Paul is facing a crisis of sorts in the church. False teaching is taking hold. The truth of the gospel is a stake. And so, by extension, is the salvation of those who fall under its spell.
Chapter one has some roundabout ways of setting up the next five chapters. While at some points it might feel disjointed, we'll break down its key points in a way that brings clarity to where Paul is taking us.
First, here's a summary of the three main sections of Galatians:
Chapters 1 & 2 deal primarily with Paul apostolic authority.
Chapters 3 & 4 deal primarily with the truth of justification by faith apart from works of the law.
Chapters 5 & 6 deal primarily how the truth of chapters 3 & 4 is lived