I like Feynman's take that "I don't feel frightened by not knowing things, by being lost in the mysterious universe without having any purpose which is the way it really is as far as I can tell"

https://www.youtube.com/watch?v=E1RqTP5Unr4

The true believers in Christianity have to know, their world view is hinged on knowing that there is a god, that the world was created in 7 days, and that the earth is only 6,000 years old, among many other questionable religious beliefs. They're wrong about all of it (IMHO as someone who grew up Catholic), but at least in their own minds, they know. And that's good enough for them, they don't have to ask any more questions because a book written by kings told them so.