'Judaism' in the Bible

For you have heard about my former way of life in Judaism: I persecuted God’s church to an extreme degree and tried to destroy it.

I advanced in Judaism beyond many contemporaries among my people, because I was extremely zealous for the traditions of my ancestors.

But when I saw that they were not being straightforward about the truth of the gospel, I told Cephas (Peter) in front of everyone, “If you, being a Jew, live [as you have been living] like a Gentile and not like a Jew, how is it that you are [now virtually] forcing the Gentiles to live like Jews [if they want to eat with you]?”