Paul gives a little more of his chronology. He got approval from the apostles (after 14 years). That's a long time between the calling from God and his full-time ministry. It is easy to get in a hurry.
Even Peter and Barnabas get caught in the ethnic divide. They were willing to compormise justification by grace to keep the peace. Paul's confrontation of them was direct (literally, in his face) and public. To think you can earn even some of your righteousness from working at the law is to miss the gospel.
Galatians 2:20 is so central. Christ lives in me. That is a resurrection promise to me after I have been crucified with him. I identify with him in his crucifixion and his resurrection. He loves me and gave himself for me. All the Christian life is the Christ life, in me.