A centerpiece of Paul’s letters is that the Good News of the Jewish messiah Jesus is for everyone, and by everyone he means Jews and Gentiles. Paul argued that Gentiles could be fully part of the family of Israel’s God just the way they are, as Gentiles, without adopting Jewish laws and traditions first. The idea was radical enough to ruffle the feathers of even some of Jesus’s other followers (Paul mentions in the book of Galatians a run-in with Peter).
Jesus was a surprise ending; a crucified and risen messiah wasn’t something Israel’s story was set up to handle. Yet, for Paul, this is how Israel’s God was now moving in the world.
To get this radical idea across, Paul had to reimagine his Scripture, transforming it from a local and ethnic story into a universal story around Jesus. Paul even wound up declaring parts of Israel’s story null and void.
If you are expecting Paul to read the Bible like it was set in stone, you will find yourself getting pretty nervous. For Paul, now that Jesus has come, the Bible was more like clay to be molded.