J.C. Ryle ~
When Peter came to Antioch, I opposed him to his face, because he was clearly in the wrong. Before certain men came from James, he used to eat with the Gentiles. But when they arrived, he began to draw back and separate himself from the Gentiles because he was afraid of those who belonged to the circumcision group.
The other Jews joined him in his hypocrisy, so that by their hypocrisy even Barnabas was led astray. When I saw that they were not acting in line with the truth of the gospel, I said to Peter in front of them all, “You are a Jew, yet you live like a Gentile and not like a Jew. How is it, then, that you force Gentiles to follow Jewish customs?”
We who are Jews by birth and not “Gentile sinners” know that a man is not justified by observing the law, but by faith in Jesus Christ. So we, too, have put our faith in Christ Jesus that we may be justified by faith in Christ and not by observing the law, because by observing the law no one will be justified. Galatians 2:11-16