I've had many different beliefs, but almost all of them involve some type of afterlife or reincarnation.
I believe in Heaven currently.
From ages 6 to 12, I really felt like there was nothing after it all, and that one day all of my experiences and memories would disappear and I'd never even know that I was once alive, which fucked me up.
I think that, even if I was convinced that there is no afterlife, I would still force myself to believe it so I don't go insane.
Even at 10, I was getting into "if there's no afterlife, then maybe I should just die now" territory.