Christians tend to pick and choose which parts of their word of God are actually infallible and which parts don’t apply anymore. There’s no reason to think God changed His mind on gay sex, tattoos, or wearing garments of mixed materials, because there was no justification for banning them in the first place. If a Christian is a true believer, they should be satisfied with “God said it, so it must be true”.

That’s the problem with relying on an external authority for morality. When it tells you to do something you don’t like, you have to either change your behavior accordingly or realize that you actually don’t trust it as an authority. Christians being by and large massive hypocrites, they tend to do the latter without admitting to it. Because if they did admit it, they wouldn’t be Christians anymore.

It’s pretty rare to find someone who genuinely takes it all on faith, that stealing cookies from the cookie jar indeed warrants eternal punishment. For everyone else, if they were honest with themselves, they would admit that if you only follow the rules you agree with, they were never actually rules for you.