God exists.
I am, and have been for years, under the impression that there is no God. Over the years, I have seen, heard about, or read about more reasons NOT to believe than to believe in God. Perfect example--9/11. If there was a God, he would not let his people do this to each other. This goes for the Holocaust as well. Why would God want this many people to be mercilessly killed? As a young child, of course, I believed in God, because I was told there was a God and I was raised to believe that. Technically speaking, I am Jewish, and I should believe that we are God's chosen people and that he is merciful and all of that. At this point, I think that it's all absolute crap. There is no reason to; there is no life changing event that I've experienced that makes me believe, or even want to believe, what everyone tells me to. I stopped believing when I was younger, and never looked back. I think the time I really decided I didn't believe in God was in third grade, when my great grandmother was dying of Alzheimer's. She had done nothing wrong, and if there was a God, he would have saved her, along with anyone else with that terrible disease. I could think of no reason for her life to be taken away, and to this day I still can't. I refuse to believe that a God would allow such a horrible thing to happen to anyone, and to allow someone to die in such a terrible way. That just wouldn't happen, and it has led me to believe that there is no God.
