What makes someone spiritual?
How do we evaluate who is a good Christian and who is not?
This is the core issue in the book of Galatians. Paul went in preaching a message of Christ, not culture. The church in Galatia was being tempted to add Jewishness to their faith, and Paul wants none of it.
Try your best to read between the lines of Galatians 3:1-3.
It’s not too difficult to see Paul’s feelings. He is extremely angry. Nowhere else in Paul’s writings do we see him insulting a church so much! Paul is telling them they started with the Spirit. The beginning of their journey with God was salvation. Salvation was completely an act of God, nothing of themselves. Now they were changing the rules and relying on the flesh.
Why did they trust God to get saved but now trust something physical such as circumcision to be righteous, or pleasing to God?