Mankind believes in God because most of mankind cannot help themselves to not believe. The majority of Mankind appears to need simple answers when something is unexplainable (how we got here), or horribly indifferent.
God or religion is like comfort food for even those who are intelligent and inventive. Just look at 9-11 and the collapse of the Twin Towers.
For the past 10 years I have listened to "God Bless America" to honor the victims. Every time I hear "God Bless America" I see two large jet planes hitting the World Trade Center, I see trapped people, fire licking at their feet, hurtling out of windows, I hear their loud thuds as they hit the side walks, I wonder if they were singing "God Bless America" as they came down, I see the unbelievable image of two massive buildings collapsing into a pile of dust, rubble and molecules, trapping numerous firefighters and others-----Two 1,500 foot buildings that disappear!
"God Bless America'? You have got to be kidding! How about "God Bless the Holocaust" as a memorial to the 11,000,000 victims each May when Germany was defeated?
Given this--we will continue to sing "God Bless" anything, in order to try and get comfort that,(though there isn't), some sense to be made of this glorious thing called life---a grand experiment.