WASHINGTON -- When Mitt Romney's father ran for the presidency 40 years ago, his Mormonism was not an issue. When Mo Udall was a major challenger for the Democratic nomination in 1976, his religion was so irrelevant that today most people don't even remember that Udall was a Mormon.

Five members of the Senate are Mormon. Are there any intimations that the Mormonism of Harry Reid, Orrin Hatch, Gordon Smith, Michael Crapo or Robert Bennett corrupts, distorts or in any way diminishes their ability to perform their constitutional duties?

Mormonism should be a total irrelevancy in any political campaign. It is not. Which is why Mitt Romney had to deliver his JFK "religion speech" this week. He didn't want to. But he figured that he had to. Why? Because he's being overtaken in Iowa. Why Iowa? Because about 40 percent of the Republican caucus voters in 2000 were self-described "Christian conservatives" -- twice the number of those in New Hampshire, for example -- and, for many of them, Mormonism is a Christian heresy.

That didn't seem to matter for much of this year when Romney had a commanding lead and his religion seemed a manageable political problem -- until Mike Huckabee came along and caught up to Romney in the Iowa polls.

The appealing aspects of Huckabee's politics and persona account for much of this. But part of his rise in Iowa is attributable to something rather less appealing: playing the religion card. The other major candidates -- John McCain, Rudy Giuliani and Fred Thompson -- either never figured out how to use it or had the decency to refuse to deploy it.

Huckabee has exploited Romney's Mormonism with an egregious subtlety. Huckabee is running a very effective ad in Iowa about religion. "Faith doesn't just influence me," he says on camera, "it really defines me." The ad then hails him as a "Christian leader."

Forget the implications of the idea that being a "Christian leader" is some special qualification for the presidency of a country whose Constitution (Article VI) explicitly rejects any religious test for office.

Just imagine that Huckabee were running one-on-one in Iowa against Joe Lieberman. (It's a thought experiment. Stay with me.) If he had run the same ad in those circumstances, it would have raised an outcry. The subtext -- who's the Christian in this race? -- would have been too obvious to ignore, the appeal to bigotry too clear.

Well, Huckabee is running against Romney (the other GOP candidates are non-factors in Iowa) and he knows that many Christian conservatives, particularly those who have an affinity with Huckabee's highly paraded evangelical Christianity, consider Romney's faith a decidedly non-Christian cult.

Huckabee has been asked about this view that Mormonism is a cult. He dodges and dances. "If I'm invited to be the president of a theological school, that'll be a perfectly appropriate question," he says, "but to be the president of the United States, I don't know that that's going to be the most important issue that I'll be facing when I'm sworn in."

Hmmm. So it is an issue, Huckabee avers. But not a very important one. And he's not going to pronounce upon it. Nice straddle, leaving the question unanswered and still open -- the kind of maneuver one comes to expect from slick former governors of Arkansas lusting for the presidency.

And by Huckabee's own logic, since he is not running for head of a theological college, what is he doing proclaiming himself a "Christian leader" in an ad promoting himself for (BEG ITAL)president(END ITAL)?

Answer: Having the issue every which way. Seeming to take the high road of tolerance by refusing to declare Mormonism a cult, indeed declaring himself above the issue -- yet clearly playing to that prejudice by leaving the question ambiguous, while making sure everyone knows that he, for one, is a "Christian leader."

The God of the Founders, the God on the coinage, the God for whom Lincoln proclaimed Thanksgiving Day is the ineffable, ecumenical, nonsectarian Providence of the American civil religion whose relation to this blessed land is without appeal to any particular testament or ritual.

Every mention of God in every inaugural address in American history refers to the deity in this kind of all-embracing, universal, nondenominational way. (The one exception: William Henry Harrison. He caught cold delivering that inaugural address. Thirty-one days later, he was dead. Draw your own conclusion.) I suspect that neither Jefferson's Providence nor Washington's Great Author nor Lincoln's Almighty would look kindly on the exploitation of religious differences for political gain. It is un-American. It is unfortunate that Romney has had to justify himself in response.