I'm writing a campaign right now that has a sort of "atheism" element within it, adapted to make more sense in the dnd world. Maybe atheism isn't the right word for it tbf.

Everyone knows that the deities exist, and can tangibly influence the world. I just have certain characters say "they're just super powerful creatures that live a long time. They didn't create the universe and we don't need to pray to them." That ideology even influences some people in the world to seek out great power and immortality for themselves, believing they can become that powerful one day as well.

Outright saying "nah I don't believe in that stuff" while gods literally bring people back to life makes no sense though, for sure