There are some disingenuous definitions in wide usage that tend to prevent productive conversation on this topic. On the one hand, there are people for whom the word "religion" connotes images of soap-box evangelists holding unnecessarily graphic images of aborted fetuses and hollering about murder; who recall hateful or homophobic rhetoric whenever they hear the word "Christian," for example. For these people, politics is an obviously separate thing -- the distinction is clear, and should be enforced. Not much else needs to be added. And insofar as this is what is meant by "religion," anybody in their right mind should think it should be separated from "politics."
However, if we take a broader definition of "religion" -- so broad that we include metaphysical assumptions and ethical convictions, regardless of their source, to qualify as "religious" (that is, if we allow that any non-rational conviction is effectively religious in nature), then fertile ground rises to meet us.
Alexis de Toqueville has been quoted often saying something like, "Democracy will fail when people realize they can vote themselves money." That's a reasonable paraphrase. The original is from Democracy in America, and it goes, "Democracy will last until the public realizes that it can vote itself largesse from the public trough." This is exactly the kind of statement that only a Frenchman could make about America, and it's so close to being true.
In fact, Toqueville's right: Democracy will fail when people realize all of that. So why haven't they realized it? The answer (and this is my thesis) is that religious sentiment, however latent it has become, has prevented most people in America from even considering this possibility.
Of course, it does not matter at all which religion the people follow -- the faith's the stuff, the confidence itself. But without it, a Democracy is a sinking ship. This religious sentiment is, as far as I can tell, the only thing that has prevented all of Marx's claims about the inevitability of the socialist revolution and the communist society from taking place. So why won't it go away? Why did we get Thoreau in 1854 while Europe got Marx in 1848? Why are there still "voices saying ex cathedra?"
That's a question better left in question form than answered, much like Jesus' "Answer me, and I will tell you by what authority I am doing these things" (Mark 11: 29).
But consider this: in William Bradford's very influential memoir, Of Plymouth Plantation (1635), which described the lives of the "pilgrims" in the early colonial days, he titles part of chapter 23, "Prosperity weakens community." In that section, he writes,
Also the people of the plantation begin to grow in their outward estates, by reason of the flowing of many people into the country, especially into the Bay of the Massachusetts, by which means corn and cattle rose to a great price, by which many were much enriched, and commodities grew plentiful; and yet in other regards this benefit turned to their hurt, and this accession of strength to their weakness. For now as their stocks increased, and the increase vendible, there was no longer any holding them together, but now they must of necessity go to their great lots... And no man now thought he could live, except he had cattle and a great deal of ground to keep them, all striving to increase their stocks. By which means they were scattered all over the bay, quickly, and the town, in which they lived compactly till now, was left very thin, and in a short time almost desolate. And if this had been all, it had been less, though too much; but the church must also be divided, and those that had lived so long together in Christian and comfortable fellowship must now part and suffer many divisions.Roman or Christian, Greek or Jew, Virginia Trading Company or Masschusetts Bay Colony? If you thirst for water, Rome's the place. If you're looking for G-d, go to Jerusalem. Buddha and Jesus said the same: give up all that you have or you can't follow me. Religion and politics aren't two separate things -- they exist together on a sliding scale much as we conceive Democrat and Republican to exist. There is no intersection, no compromise that isn't cowardice. And, oh yeah, what-is-called "politics" won this dialectical contest long, long ago; and what is called "religion" only exists in brief experiments like Brook Farm, Fourier's imagination, and Haight Ashbury for about ten minutes in 1966. And maybe in parts of the Amazon.
[Then Bradford describes a land-redistribution act that was intended "to prevent any further scattering... and weakening.] But alas! this remedy proved worse than the disease; for within a few years those that had thus got footing there rent themselves away, partly by force, and partly by wearing the rest with importunity and pleas of necessity, so as they must either suffer them to go, or live in continual opposition and contention. And others still, as they conceived themselves straitened, or to want accomodation, break away under one pretense or other, thinking their own conceived necessity, and the example of others, a warrant sufficient for them. And this, I fear, will be the ruin of New England, at least of the churches of God there, and will provoke the Lord's displeasure against them.
Before I end this "Part 1," I want to say that I am using a concept of religion that approaches Bradford's much more closely than it could be associated with Pat Robertson's. For Bradford, "the church" was the social contract, the community itself -- there was to be no other. See also, the early church described in Acts. For Robertson, "the church" is a money-making machine intended mostly to make deluded hillbillies fully-insane.
[Tomorrow I'll totally reverse all of this to write a post describing The Federalist Papers as religious documents, and argue that there is only ever compromise, and that our task should be to make the intersection perfectly perpendicular... uh, like a cross, I guess.]