It's because deep down they do believe in God. We are born knowing. It is just they are ticked at him because of some trauma that happened or disillusioned because they were fed religious nonsense when growing up. It's like when a 2 year old wants a pony and the parents don't give their 2 year old the pony...so the child screams and says well I'm not gonna pay attention to you anymore until I get what I want. for real truth look up Red Elk.