Why don't you believe in a god?

[Akvod]

Chairman-Mao said:

I do believe in a God because something had to create the world. I find it hard to believe a "big bang" created a world and made life possible, that just sounds stupid to me. Now I'm no expert on either religion or science (relating to the big bang theory) but I choose to believe in religion instead of science.

But why create an explanation without proof? Why can't you simply say "I dunno"?

And both non-religious and religious people believe in the universe. Religious people go an extra step and believe in a god? Why go that extra step? It's unnecessary.