Daniel Dennett pointed out that George Bush and virtually all Christians don't really have faith in God. They have faith in faith. They have faith in that being Christian is good for the world. But they don't really have faith in all the supernatural stuff.
According to most Christian interpretations of the various Bibles this life is only about gathering brownie points for the next. So why doesn't sell all their stuff and go to India like mother Theresa and help the poor? Why bother making a career in a company? Why bother trying to become the president in USA? Why bother making this life comfortable at all? This life is just a short interlude before the real life, which obviously will be so much better and go on for so much longer. Our short little time here, hardly compares to eternity, does it?
I'm sure a lot of Christians have guilt about not having this kind of strong faith, which confusing enough has become an intrinsic part of Christian culture.
There are many philosophical and psychological theories on why people are Christian in spite of this, so I won't go into details. But I think Nietzsche's is a compelling one.
...and then we've got Foucault's theory that all of us in the west are Christians anyway, no matter how atheist we claim we are. He claims that Christianity is a lot deeper than just faith. He thinks it's an entire system to view and understand the world with we cannot shed without replacing it with something else first. I'm inclined to believe this to. I think it'll be many generations before we realize what it really means to be atheist.
My long winded point is that I don't think that Bush has faith in his invisible friend. He is first and foremost guided by reality. I just think he uses "God" to make him feel better about taking decisions which break his sense of morality... ie because that's what he convinces himself God wants. Atheists in power will still need to make uncomfortable decisions. I think the end result will be the same.
And isn't all democracies really ruled by surveys anyway? Is it really relevant who sits at the wheel?
edit: I don't worry about religion anymore. All research shows that religion since the enlightenment has been slowly dying out. I think the death of God is inevitable. Today it's the educated and young who reject God. And people aren't getting less educated. And if Foucault is right, even Christians today are equally guilty of promoting this shift away from the Christian paradigm of thought. Chances are pretty good that in the future we'll still have Christians, but their faith will be so radically changed that nobody will recognize it. Christianity never stopped evolving. Christian philosophy is an ever changing project.