The pope might have had a word with any king or priest that tried to push the wrong things into peoples head though. It wasn't like a do whatever concept. You'd had to have broad support in the ruling class.

For the big things, yes. But for matters of community, or trivialities of daily lives, the words of the clergy might as well have been words of god. You can still see this today, for example in countrysides of various Christian countries, where the local priests are given authority and respect by default, and when they e.g. start hinting that one political option is good and the other is evil, people end up voting just like the priests hinted.