Galatians 2:14
When I saw that they were not acting in line with the truth of the gospel, I said to Cephas in front of them all: 'If you, though a Jew, live like a Gentile and not like a Jew, how can you compel the Gentiles to live like Jews?' — Paul's public rebuke ('apeipon') to Peter ('Kēphas') challenges the internal contradiction: Peter's own behavior already demonstrates that Torah observance is not necessary for believers, yet his withdrawal from Gentiles implies the opposite, betraying the gospel's truth ('alētheia').