Over many centuries the church has appealed to the memory of Paul and has laid on the convert from Judaism the yoke of refraining from keeping the traditional law. When he has not conformed completely to his Gentile environment, he has been suspected of Judaizing, or of merely nominal conformity to the dominant religion. Yet the facts of Paul’s continuing conformity to the practices of traditional Judaism are there plainly on the face of Scripture, for those willing to find them. The contortions of many commentators faced with Paul’s acceptance of the suggestion made by James that he should associate himself with the men who had taken a Nazirite vow (Acts 21:23, 24) would be ludicrous, if they were not often tragic. …
… When Paul says, “I have become all things to all men,” he is really saying that he is so at Christ’s disposal that there is nothing in his own peculiarities and practices that could be used to erect a barrier between his Lord and those to whom he would reveal himself. When all is said and done, how many, when they first hear of Jesus of Nazareth, are really conscious that they are being introduced to an observant Jew from Palestine? Even so Paul claims that his life has taken on the pattern willed by his Lord for him. Because this pattern was not forced on him from outside but moulded him from within, his own peculiarities ceased to impose themselves on others when he spoke to them about his Lord.
H. L. Ellison, “Paul and the Law – “All Things to All Men”,” W. Ward Gasque & Ralph P. Martin, eds., Apostolic History and the Gospel. Biblical and Historical Essays Presented to F.F. Bruce. Exeter: The Paternoster Press, 1970. Hbk. ISBN: 085364098X. pp.201-202. As reprinted online here.