There's been a lively discussion of Mark Lilla's superb book on the history of political theology over at Cato Unbound. Mark's opening essay is here. Damon Linker responds here; Philip Jenkins here. My own contribution is here. My bottom line:
America is substantively and experientially a deeply religious country, and its political discourse has always been saturated with religious rhetoric and imagery. I don't think Mark or I would dispute this. It is a country whose politics is experientially creedal. It doesn't incubate the kind of high Tory pragmatism that I admire in the English experience; or even the kind of atheist secularism that helped spawn socialism in other developed countries in the twentieth century. But the power of that religious presence I call it "Christianism" and describe it at length in The Conservative Soul is in many ways a testament to the strength of the secular constitution that resists it. In fact, I think that without the kind of secularism that Mark detects in the founding documents and Constitution, America would long since have succumbed to some version of theocracy or another.