I read this blog. It’s about priests doubting, losing faith, or disagreeing with the theology of their church. Go read it.
Seriously, go read it, then come back.
Assuming you did, now consider this. What if you were a jewish rabbi in the iron age, and you didn’t agree with the scriptures about stoning your son to death for disobedience or working on the sabbath being automatically punishable by death or eating the wrong food making you evil, or burnt animal sacrifice when your village was starving already. Lets say you lost faith in your religion, if not your god.
So you start teaching some different ideas, trying to square them with scripture however you can, but at some point you can’t, so you break off and form your own theology/philosophy, primarily rooted in disagreeing with the doctrines of your former faith. You, believing in a creator that inspires his followers to follow his wishes, would assume as many believers do today that the ideas in your head came from yahweh.
You get a following, turns out there are tons of people fed up with all of that stuff too.
Then politics are politics, you get put to death. But the movement doesn’t end there, your followers use the momentum surrounding your rise and fall to build a whole new faith based on what they see as the good from their former religion and the good from your teachings. And eh, so a few miracle stories gain some popularity, it can only help the popularity of this new faith, right?
It’s something to ponder.