Paul didn't just disagree with Peter; he confronted him face-to-face in front of everyone. Why such a public display?
When Peter came to Antioch, Paul saw something deeply troubling. Peter, who knew the gospel's truth about freedom from the Law for Gentiles, started acting as if he wasn't free. He separated himself from the Gentile believers, likely due to the arrival of some stricter Jewish Christians from Jerusalem.
Paul's response was immediate and public. He 'opposed him to his face.' This wasn't a private whisper or a backhanded compliment; it was a direct confrontation. The commentators agree: this was necessary because Peter's actions were leading others astray and undermining the very truth of the gospel Paul preached. It wasn't about personal pride, but about protecting the integrity of the message of salvation by faith, not by following Jewish laws.