And they are informed of thee - Reports respecting the conduct of Paul would be likely to be in circulation among all at Jerusalem. His remarkable conversion, his distinguished zeal, his success among the Gentiles, would make his conduct a subject of special interest. Evil-minded men among the Jews, who came up to Jerusalem from different places where he had been, would be likely to represent him as the decided enemy of the laws of Moses, and these reports would be likely to reach the ears of the Jewish converts. The reports, as they gained ground, would be greatly magnified, until suspicion might be excited among the Christians at Jerusalem that he was, as he was reputed to be, the settled foe of the Jewish rites and customs.
That thou teachest all the Jews ... - From all the evidence which we have of his conduct, this report was incorrect and slanderous. The truth appears to have been, that he did not enjoin the observance of those laws on the Gentile converts; that the effect of his ministry on them was to lead them to suppose that their observance was not necessary - contrary to the doctrines of the Judaizing teachers (see Acts 15); and that he argued with the Jews themselves, where it could be done, against the obligation of those laws and customs since the Messiah had come. The Jews depended on their observance for justification and salvation. This Paul strenuously opposed; and this view he defended at length in the Epistles which he wrote. See the Epistles to the Romans, the Galatians, and the Hebrews. Yet these facts might be easily misunderstood and perverted, so as to give rise to the slanderous report that he was the enemy of Moses and the Law.
Which are among the Gentiles - Who live in pagan countries. The Jews were extensively scattered and settled in all the large towns and cities of the Roman empire.
To forsake Moses - The Law and the authority of Moses. That is, to regard his laws as no longer binding.
To walk after the customs - To observe the institutions of the Mosaic ritual. See the notes on Acts 6:14. The word “customs” denotes “the rites of the Mosaic economy the offering of sacrifices, incense, the oblations, anointings, festivals, etc., which the Law of Moses prescribed.”