Some of us decide there isn't any God, and are willing to fight for that, too.
You know, I never liked St. Paul much; he's not Jesus and he's very crabby. But as I take him as a severely flawed human being who does the best he can, well, I like him better with each passing year. Besides, I'm flawed, crabby, and I'm not Jesus, either.
The story of how Paul lifted Greco-Roman paganism and ushered in the modern world by turning it toward the true and living God is related in an fascinating work by Sir William Ramsay, who later was awarded the Nobel Prize in chemistry. (Not that that matters, but it does mean the source isn't some crank like me.) It was written in 1897, and is available in full here.
The surprise is that notorious cementhead Paul didn't replace Zeus & Co. with the mystical Christ who died for everybody's sins, but began by steering the already extant hunger for and love of Good toward its true source, the God of All Things.
This God was not terribly different from Aristotle's theoretical and philosophical God, except Aristotle's was devoid of mercy and love, which are essential components of All Things. Neither would an Aristotle suffer as Paul did for a god bereft of these things: that God is kinda mellow and laissez-faire, not worth dying for or even preaching about. So the majority of the Hellenic world still sacrificed to Zeus and his crew.
"(W)e turn to the speech at Athens. So far was Paul from inveighing against the objects of Athenian veneration that he expressly commended the religious feelings of the people, and identified the God whom he had come to preach with the god whom they were blindly worshipping.
He did not rebuke or check their religious ideas, but merely tried to guide them; he distinctly set forth the principle that the pagans were honestly striving to worship "the God that made the world and all things therein".
In this speech Paul lays no emphasis on the personality of the God whom he sets forth: "what ye worship in ignorance, this set I forth unto you,"and "we ought not to think that the Divine nature is like unto gold or silver or stone, graven by art and device of man".
The popular philosophy inclined towards Pantheism, the popular religion was Polytheistic; but Paul starts from the simplest platform common to both---there exists something in the way of a Divine nature which the religious try to please and the philosophers try to understand."
This is the One, True, and Living God who is or should be recognizable to Jew, Christian, and Muslim alike, Aristotelians and Deists, and even to the pagans whom Paul converted. In our doctrinal thises-and-thats, we so often lose sight of that God, and certainly if the West is to achieve a rapprochement with the Muslim world, (which respected Aristotle so much they called him the "First Teacher"), we're going to have to have the wisdom of Paul to locate Him and make Him our common ground.
And if our militantly secular friends are going to get along with the billion and a half Muslims on this earth, they need to leave a little breathing room in things for this Living God. Mebbe they could start with the Jews and Christians already in their own countries, just to practice up. We gotta get back to the basics---if prickly Paul could touch the human heart instead of bashing brains, surely the more highly evolved children of the Enlightenment can do as well as some crabby ol' cementhead.
(Personal note---I wrote this a few days ago and thought it might be too "We Are the World." But after Pope Benedict's very important words yesterday, I realize some things can't be said too often. We are the world, and that's an empirically provable fact. Kumbaya, y'all.)