Galatians 2:12

For before that certain came from James

(προ του γαρ ελθειν τινας απο Ιακωβου). The reason (γαρ) for Paul's condemnation of Peter. Articular infinitive in the genitive after προ with the accusative of general reference (τινας), "for before the coming as to some from James." Does Paul mean to say that these "certain" ones had been sent by James to Antioch to inspect the conduct of Peter and the other Jewish brethren? Some scholars think so. No doubt these brethren let the idea get out that they were emissaries "from James." But that idea is inconsistent with the position of James as president of the conference and the author of the resolution securing liberty to the Gentile Christians. No doubt these brethren threatened Peter to tell James and the church about his conduct and they reminded Peter of his previous arraignment before the Jerusalem Church on this very charge (Acts 11:1-18). As a matter of fact the Jerusalem Conference did not discuss the matter of social relations between Jews and Gentiles though that was the charge made against Peter (Acts 11:1).He did eat with the Gentiles

(μετα των εθνων συνησθιεν). It was his habit (imperfect tense).He drew back

(υπεστελλεν). Imperfect tense, inchoative action, "he began to draw himself (εαυτον) back." Old word υποστελλω. See middle voice to dissemble (Acts 20:20; Acts 20:27), to shrink (Hebrews 10:38).Separated himself

(αφωριζεν εαυτον). Inchoative imperfect again, "began to separate himself" just like a Pharisee (see on Galatians 1:15) and as if afraid of the Judaizers in the Jerusalem Church, perhaps half afraid that James might not endorse what he had been doing.Fearing them that were of the circumcision

(φοβουμενος τους εκ περιτομης). This was the real reason for Peter's cowardice. See Acts 11:2 for " ο εκ περιτομης" (they of the circumcision), the very phrase here. It was not that Peter had changed his views from the Jerusalem resolutions. It was pure fear of trouble to himself as in the denials at the trial of Christ.