Why did Peter withdraw from eating with Gentiles at Antioch?
Peter withdrew because he was afraid of what the Jews from Jerusalem might say. He still struggled to accept that he was no longer under the law and was free to eat and converse with Gentiles. The practice still bothered him, and he was not yet fully convinced Paul was on the right track.
Les explains that Peter's problem was that he just couldn't recognize that he was no longer under the law and that he was free now to eat with Gentiles and to converse with Gentiles. It still bothered him. In Galatians chapter 2, it was such a bother that even though Peter was visiting the Gentile church at Antioch and evidently had been going in and eating with those Gentiles, just as soon as some Jews came up from Jerusalem, Peter withdrew because he was afraid of what the Jews might say. Les points out that this is real, that these are normal people, and that Peter was not yet that convinced that Paul was on the right track. This follows the confrontation where Paul withstood Peter to the face because he was to be blamed.