But when I saw that they walked not uprightly according to the truth of the gospel, I said unto Peter before them all, If thou, being a Jew, livest after the manner of Gentiles, and not as do the Jews, why compellest thou the Gentiles to live as do the Jews?
Walked not uprightly, х orthopodousin (G3716)] - 'are not walking with straightforward steps.' Compare Galatians 6:16.
The truth of the Gospel - which teaches that justification by legal observances is inconsistent with redemption by Christ. Paul alone maintained the truth against Judaism, as afterward against paganism (2 Timothy 4:16-17).
Peter - `Cephas' in the oldest manuscripts.
Before them all (1 Timothy 5:20). A public scandal could not be privately remedied.
If thou ... - "If thou," though a Jew (and therefore more bound to the law than the Gentiles), livest (habitually from conviction, Galatians 2:12; Acts 15:10-11) as a Gentile (freely eating of every food, and living as if legal ordinances in no way justify, Galatians 2:12) and not as a Jew, how is it that (so 'Aleph (') A C Delta G f g, Vulgate, read for 'why,' which B reads) thou 'art compelling (by, thine example) the Gentiles to live as do the Jews?'-literally, to Judaize; i:e., to keep Judaic ceremonies. What was formerly obedience to the law is now mere Judaism. Peter's high authority would constrain Gentile Christians to regard Judaizing as necessary to all, since Jewish Christians could not consort with Gentiles, in communion without it. But how can Peter be said to be now 'living as a Gentile?' His doing so was past (Galatians 2:12). Dr. Whately suggests. 'If thou, Jew as thou art, hast life on the same terms as a Gentile, and not by virtue of being a Jew, why dost thou compel the Gentiles to Judaize?' This suggested Peter's own statement immediately after (Acts 15:11).