For me it was quite simple - when I was growing up, my religious grandmother pretended that the tooth fairy, santa claus, christmas elves, easter bunnies etc existed, as most adults do for kids. But so do god, jesus and especially everyones personal guardian angel that keeps them safe that you should pray to.

I just stopped believing in all of them at some point once I grew up, and have yet to find any compelling evidence to suggest any of them actually exists.