that a large majority of Christians aren’t actually Christian

Yes they are, Christian doesn’t mean “good person.” It mostly means someone who believes that a sinless god-man died, and now they get to go to heaven if they want to.

With the old testiment being a different religion’s text, and the new testament being mostly made out of letters that people supposedly wrote to each other, you can make the Bible say basically anything you want it to. It’s not a consistent or coherent storyline.