The speech was written, the stagecraft set. Last Wednesday evening, about 12 hours before he was to speak on faith and public life as the guest of George H.W. Bush in College Station, Texas, Mitt Romney was musing aloud about the task before him. The former Massachusetts governor was happy with the text, which had taken him nearly a week to write and polish: it was rife with allusions to the Founding Fathers and to what Romney called "our grand tradition of religious tolerance and liberty." He was thrilled, too, that the 41st president was going to introduce him; Romney would not have chosen the Bush library as the venue if the senior President Bush had declined to be there. (Bush 41 offered no endorsement, but tacit benediction—and, before the morning speech, cold cereal, which Romney declined, leaving the former president to have a bowl by himself while the governor drank a caffeine-free Diet Coke.) "My view is that when a person of faith is running for office—particularly a person of a faith you may not be familiar with—there are some questions that are legitimate," Romney said from the road in Houston. Would the authorities of a president's church exert influence on White House decisions? Would a president of a given faith put his country's traditions and laws above those of his church's? "Those are real issues, and people have a right to hear a candidate address them," Romney said. But there had to be a line drawn somewhere: "There are some particular doctrines, some theological concepts, that we don't need to go into, no matter what faith it is."

Or so Romney hopes—and, given the poll numbers in Iowa, which votes in three weeks, perhaps prays. At almost exactly the same hour on Wednesday, Mike Huckabee was spending a rare night at home in Little Rock, packing for a campaign trip to South Carolina. In a telephone interview with NEWSWEEK'S Holly Bailey, Huckabee, an ordained Southern Baptist minister, declined to say whether he agreed with evangelical Christians who believe Mormonism is a heretical cult. "First of all, I don't think it's appropriate for me to start evaluating other religions," Huckabee said. "The more I answer these questions, the more people want to say, 'Ah, you describe yourself as a theologian,' or 'Oh, you're the one who is setting yourself up as a judge of religions.' I am damned if I do; I am damned if I don't."

Then he did. Asked if he thought Scriptural revelations from God ended when the Bible was completed, Huckabee said: "I don't have any evidence or indication that he's handed us a new book to add to the ones, the 66, that were canonized in 325 A.D. … It was a careful process that adopted those books. That was something I did study in college and seminary … the process by which we ended up with those books. I don't know that there's any other books."

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Which no doubt comes as a surprise to the world's nearly 13 million members of the Church of Jesus Christ of Latter-day Saints, who, like Romney, believe that God did indeed reveal another text in 19th-century America, the Book of Mormon. For Huckabee, such a disagreement in a matter of faith can be no small thing. In an ad, he is styled as a "Christian leader" and says, "Faith doesn't just influence me; it really defines me."

So it has come to this: the 2008 Republican Iowa caucuses have descended into a kind of holy war. The clash centers on issues that are, in Saint Augustine's phrase, ever ancient, ever new: the nature of God, the disposition of power and the sanctity of conscience. The skirmish pits Huckabee against Romney in a story of hardball politics and high-minded history, of shadowy slurs and noble principles.

Fights about faith and politics have been with us always. In 1800, there were advertisements saying voters could have "Adams and God, or Jefferson and no God." Andrew Jackson resisted the formation of a "Christian Party in Politics." Abraham Lincoln buried a proposed constitutional amendment designed to declare the nation's dependence on, and allegiance to, Jesus. A century ago, in the 1908 campaign, William Howard Taft, a Unitarian, was attacked as an apostate by supporters of William Jennings Bryan, an evangelical Christian. "Think of the United States with a President who does not believe that Jesus Christ was the Son of God, but looks upon our immaculate Savior as a … low, cunning imposter!" The Pentecostal Herald said in July 1908.