Why people refuse to believe God exist

There are alot of Christian topic being formed all around but no one has yet said their reasons why they don't believe in God.

Is it just because you can't see God that you feel he don't exist, or because you feel nothing should be greater than humans, or you don't just want to believe God exist?

What a sad, dark world you must live in without being able to think for yourself, having to take every single thing on the basis of blind faith.