"The same point emerges in Galatians 2.11–21. Here, beyond cavil I think, the point of vindication is not ‘how someone becomes a Christian’ but the question of table-fellowship: with whom may I, indeed must I, share table-fellowship? Peter’s action in separating himself from Christian Gentiles was not implying that they needed to perform moral good works; it was implying that they needed to become physically Jewish. Paul’s argument against him was not to do with the mechanism of how people come from being sinful idolaters to forgiven members of Christ’s people, but with the equality within the people of God of all who believe the gospel, Jew and Gentile alike. That controversy, indeed, dominates the entire letter in a way that, alas, I think Martin Luther never saw (though specialists may correct me)."