'Truth of the Gospel' in the Bible

to whom we gave place in the way of subjection, no, not for an hour; that the truth of the gospel might continue with you.

But when I saw that they walked not uprightly according to the truth of the gospel, I said unto Cephas before them all, If thou, being a Jew, livest as do the Gentiles, and not as do the Jews, how compellest thou the Gentiles to live as do the Jews?

because of the hope which is laid up for you in the heavens, whereof ye heard before in the word of the truth of the gospel,