'Truth of the Gospel' in the Bible

But we did not surrender to them even for a moment, in order that the truth of the gospel would remain with you.

But when I saw that they were not behaving consistently with the truth of the gospel, I said to Cephas in front of them all, "If you, although you are a Jew, live like a Gentile and not like a Jew, how can you try to force the Gentiles to live like Jews?"