Why do you believe in God? Not necessarily that, but the afterlife?

I'm a Christian & I've been saved for about 3 years, but all of the sudden these "what if's" have come up after I got back from a church revival (kind of defeated the purpose, huh?). I'm only 14, but I'm really curious... I know there HAS to be something that created everything - - all of this, but what exactly happens after all of this is gone? What about the afterlife? Just because some book said that our souls go somewhere if we choose to believe in Him... I believe in God because I can feel Him inside of me whenever I sing or pray and concentrate solely on Him, but it's hard for me to believe that there's a place without any pain or any hurt.. I want to be closer to God, but I would like to hear some people's standpoints on this to make me fully believe in what happens after the world is no more..