Heavens, it's getting crowded in the pews these days--at least with Democratic presidential candidates. Here is Sen. Barack Obama in California's Saddleback pulpit at the invitation of mega-selling pastor Rick Warren. There is Sen. Hillary Clinton with downcast eyes in Newsweek, praying before the cameras in New York's Riverside Church. And there preaches John Edwards, also in Riverside Church, weaving his personal faith into everything from AIDS to the minimum wage. Clearly the push is on to show that, for now anyway, the Democratic hopefuls are just plain folks in the religion department. All the more reason to plumb the...