12 For 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.
12 For before that certain came from James, he did eat with the Gentiles: but when they were come, he withdrew and separated himself, fearing them which were of the circumcision.
English Standard Version
12 For before certain men came from James, he was eating with the Gentiles; but when they came he drew back and separated himself, fearing the circumcision party.
12 Here's the situation. Earlier, before certain persons had come from James, Peter regularly ate with the non-Jews. But when that conservative group came from Jerusalem, he cautiously pulled back and put as much distance as he could manage between himself and his non-Jewish friends. That's how fearful he was of the conservative Jewish clique that's been pushing the old system of circumcision.
New King James Version
12 for before certain men came from James, he would eat with the Gentiles; but when they came, he withdrew and separated himself, fearing those who were of the circumcision.
New Living Translation
12 When he first arrived, he ate with the Gentile believers, who were not circumcised. But afterward, when some friends of James came, Peter wouldn't eat with the Gentiles anymore. He was afraid of criticism from these people who insisted on the necessity of circumcision.
Notwithstanding Peter's character, yet, when Paul saw him acting so as to hurt the truth of the gospel and the peace of the church, he was not afraid to reprove him. When he saw that Peter and the others did not live up to that principle which the gospel taught, and which they professed, namely, That by the death of Christ the partition wall between Jew and Gentile was taken down, and the observance of the law of Moses was no longer in force; as Peter's offence was public, he publicly reproved him. There is a very great difference between the prudence of St. Paul, who bore with, and used for a time, the ceremonies of the law as not sinful, and the timid conduct of St. Peter, who, by withdrawing from the Gentiles, led others to think that these ceremonies were necessary.