For almost ten years, I have participated in a book group comprising people who attended the University of Chicago. Mostly we read current novels, with a preference for those authors (Philip Roth, Saul Bellow, J. M. Coetzee) who have a connection with the school. The group includes a Marxist-leaning professor of philosophy, a childhood-development specialist, a pharmaceutical researcher, a neurologist, and an attorney.

I marvel in our meetings at how the same book can evoke radically different responses. Yet after navigating a sea of ideas, the living room conversations almost always drift back to political issues. Though I live in a red state, all but one of my book buddies are liberal Democrats—the sole exception being a libertarian who opposes nearly all government.

The group views me as a window to a parallel universe. "You know evangelicals, right?" I nod yes. "Can you explain to us why they are so opposed to homosexuals getting married?" I do my best, but the arguments I cite from leading evangelicals make little sense to this group.

After the 2004 election, the Marxist professor launched into a tirade against "right-wing evangelicals." "They're motivated by hate—sheer hate!" he said. I suggested fear as a possible alternative, fear of changes in a society that is moving in a troubling direction. "No, it's hate!" he insisted, uncharacteristically raising his voice and turning red in the face.

"Do you personally know any 'right-wing evangelicals'?" I asked. "Not really," he admitted a little sheepishly, though he said he had known many in his youth.

I have learned from this group how threatening religion can seem, especially to those who see themselves as a minority of agnostics in a land of belief. They tend to ...