There's a lovely sci-fi book series Ada Palmer's Terra Ignota where one of the speculative fiction aspects is that there had been some awful world war iii fough

There's a lovely sci-fi book series Ada Palmer's Terra Ignota where one of the speculative fiction aspects is that there had been some awful world war iii fought over religion, and the world decided to outlaw organized religion. Religion is allowed, but it's between you and your "sensayer" and they're not allowed to preach or tell you what to believe. It allows search & exploration, but everything has been set up to prevent organization. If you've read Sanderson's Mistborn, there's maybe some parallel to the Keeper Sazed, who inventories religions/beliefs & tries to help folks find beliefs that suit them.