How do we know that Peter's actions were wrong?

Peter's actions are examined through the lens of the Gospel message, which emphasizes unity among believers and the breaking down of barriers that previously existed between Jews and Gentiles. In Galatians 2:11-14, the Apostle Paul confronts Peter for withdrawing from fellowship with Gentile believers due to fear of the circumcision group. This act was directly contrary to God's revelation to Peter, as seen in Acts 10, where God had shown him that no person should be deemed unclean. By yielding to fear, Peter not only compromised his own understanding but also caused others, including Barnabas, to stumble. Thus, Paul's rebuke underscores the necessity of standing firm in the truth of the Gospel, regardless of social pressures or fear of man.