Paul's two encounters with Peter--the ones recorded in Galatians 2--demonstrate his equal standing with the first 12 as apostles of Jesus Christ.
First, at the Jerusalem conference (Vv. 1–10; Acts 15) Paul resolutely resisted having Titus--or any Gentile Christian--circumcised as a condition of salvation. Ultimately, Peter and the others extended to him "the right hand of fellowship." Such an endorsement clearly indicated that Paul's message was not only consistent with Peter's, it was identical.
The second episode occured later, down at Antioch. When Peter violated his message by withdrawing from those uncircumcised Gentile Christians, Paul took him to task. Moved by fear of what others would think, Peter's hypocrisy led all of the Jewish believers to also withdraw from the other Christians. Paul did what needed to be done. He rebuked Peter openly and to his face...because he "stood condemned."
These two scenarios did more than merely show that Paul was Peter's equal. They also highlighted the very point of doctrine Paul was arguing with this letter: "Knowing that man is not justified by works of law, but through faith of Christ Jesus, we have beleived in Christ Jesus" (Gal. 2:16).
This is a powerful message--one promised and promoted by Moses and the prophets. You should join our exploration of it.