The million dollar question! I really get peeved when asked this question especially when it comes with that disbelieving look and exclamation " You mean you really don't believe there is a god? You insane or something? Not forgetting that very annoying question "what happened to make you not believe in god? Why do people always assume something terrible must have happened for one to have lost "faith" or not have faith at all?
Well, the good news is, there was no big bang that left me gasping for faith. It just happened that I am not convinced there is a "God" designing our planets, dishing out destinies, taking care of our needs, waiting for us to ask so s/he/it shall give, busy keeping scores on our good and bad deeds. I don't believe there is an omnipotent, omniscience, all knowing being watching from high above and why not from down below anyway? I guess we don't like the idea of stepping on god! Well, high above sounds better, after all heaven or rather space looked so impenetrable but with space shuttles, not anymore!
Anyway, it is my humble opinion that man not only created God but did so in his own image! There are as many gods as there are people, communities and religions. People tend to create god that suits them and their particular situation consciously or unconsciously. No big deal about exercising our imaginations but it becomes a big deal when you judge others base on your own particular god beliefs or tried forcing your imagination down the throat of others. It is unfortunate that many believers influence state policies based on personal religious beliefs, that is a big no no. That is indeed a great injustice to those who do not share these religious beliefs either because they believe in another "God" and have different set of doctrines or simply because they have no "God" delusion.