You see, it was like this. Peter is a Jewish man, and at first he was friendly with the Christians at Antioch that were not Jews. He even broke the Jewish rules and he ate meals with them. But then James sent some other Jewish men to Antioch, and after they got there, Peter changed. These new men reckoned that every Christian has to become a Jew, and Peter was frightened of them. He went back to following the Jewish rules and stopped eating meals with those people that were not Jews. All the other Jewish Christians at Antioch were frightened too, and they did the same as Peter, even though they knew it was wrong. And Barnabas did that too. He stopped eating meals with people that are not Jews.