14. walked not uprightly--literally, "straight": "were not walking with straightforward steps." Compare Ga 6:16.
      truth of the gospel--which teaches that justification by legal works and observances is inconsistent with redemption by Christ. Paul alone here maintained the truth against Judaism, as afterwards against heathenism (2Ti 4:16, 17).
      Peter--"Cephas" in the oldest manuscripts
      before . . . all-- (1Ti 5:20).
      If thou, &c.--"If thou, although being a Jew (and therefore one who might seem to be more bound to the law than the Gentiles), livest (habitually, without scruple and from conviction, Ac 15:10, 11) as a Gentile (freely eating of every food, and living in other respects also as if legal ordinances in no way justify, Ga 2:12), and not as a Jew, how (so the oldest manuscripts read, for 'why') is it that thou art compelling (virtually, by thine example) the Gentiles to live as do the Jews?" (literally, to Judaize, that is, to keep the ceremonial customs of the Jews: What had been formerly obedience to the law, is now mere Judaism). The high authority of Peter would constrain the Gentile Christians to regard Judaizing as necessary to all, since Jewish Christians could not consort with Gentile converts in communion without it.

JFB.