Galatians 2:14

Walked not uprightly. The course of Peter, Barnabas, and the other Jews would bring confusion and division in the church. The question involved far more than the conduct of leaders. The welfare of the Gentile believers was at stake, and even the fate of the gospel itself. If the Judaizing party were permitted to have its way, then the gospel — salvation through faith in the atoning death of Jesus — would be superseded by the doctrine of salvation through the works of the law. Thus “the truth of the gospel” would no longer be proclaimed.

Before them all. The rebuke was public because the offense was public. All, or nearly all, were concerned. To Timothy, Paul later wrote that a public rebuke for open sin would effectively deter others from following the same course (see 1 Tim. 5:20). The action of Peter and the other Jews created a rift in the fellowship of the church and threatened to shatter the unity of Gentile and Jew in Christ. The prospect was disastrous. Paul addressed his remarks to Peter because his course of action was primarily responsible for the crisis that had arisen upon that occasion.

The manner of Gentiles. It had taken a miracle to convince Peter that Gentiles should be admitted to Christian fellowship on an equality with the Jews (see Acts 10:20, 28, 29, 34). Since that experience he had evidently felt free to associate with Gentiles, contrary to Jewish custom. His apparent silence, when rebuked, implies that he recognized the error of his hasty move and the seriousness of its implications for the future of the church as a universal, united body. This much may be conceded in Peter’s favor.

Why compellest thou? Peter’s sudden change of attitude would require the Gentiles to comply with the demands of the Judaizers that they be circumcised and observe Jewish rites if friendly relations between them and Jewish Christians were to continue. This would virtually be compelling the Gentiles to live like Jews. Paul here points out the inconsistency resulting from this attitude of Christian Jews toward the Gentiles in the church.