What role should faith play in American politics? How compatible is orthodox religion with the practical functioning of democracy?

Those questions are posed by leaders of the religious right, who are threatening to jump ship if the Republicans nominate Rudy Giuliani. Even the prospect of Hillary Clinton in the White House can't convince them to support a candidate who backs abortion, lived with a gay couple and married three times.

"It's not about winning elections," Texas preacher Rick Scarborough told The New York Times. "It's about honoring Christ." James Dobson, the influential radio host, adds: "Polls don't measure right and wrong; voting according to the possibility of winning or losing can lead directly to the compromise of one's principles."

The religious right has won a seat at the table of power, fair and square. The issue now is how they've used that power. There's nothing wrong with "honoring Christ"; there is something very wrong when one faction believes it is on a mission from God; that it has a monopoly on moral truth.

Dobson might scorn "compromise," but that's what politics is all about. Compromise is not a swear word, it's an absolute necessity. This is a very large and diverse country, and the only way it can be governed effectively is through accommodation, flexibility and tolerance.

But the Scarboroughs and Dobsons seem intent on living up to the phrase John McCain used about them a few years ago "agents of intolerance." (This is not a partisan point. The pro-choice wing of the Democratic Party can be just as intolerant of dissent as pro-life evangelicals.)

Nobody is more thrilled by the self-righteousness of the religious right than the Democratic Left. Hillary Clinton and Nancy Pelosi are praying yes, some liberals do pray for a conservative defection next year. Heck, they'll be writing checks, holding fund-raisers, organizing Tupperware parties anything to do to the Republican nominee what Ralph Nader did to Al Gore seven years ago.

Most sane conservatives are appalled at any talk of a third party, or even a sit-on-your-hands approach. Right-wing talk-show host Sean Hannity could not contain his frustration, telling Dobson repeatedly during an interview this week that if he persists in his views, "the result will be far worse for the cause that I know you passionately and deeply believe in."

"It will be terrible, Sean," Dobson conceded. "That's absolutely true." But purity, he kept insisting, is more important than practicality. God forbid we soil our hands by recognizing reality.

Dobson and company are not just reflecting a fear of Giuliani. As the national debate has focused on new issues such as Iraq and health care and moved away from the social agenda of abortion and gay rights, religious leaders have lost influence and visibility. If they threaten to bolt, people pay attention.

And dissatisfaction is a permanent state of mind for any member of what Newt Gingrich once derided as the "perfectionist caucus." Nobody is good enough. The religious right criticized Ronald Reagan, after all, and Dobson doesn't like McCain or Fred Thompson, either.

Let's be clear: Religion has an important place in public life. And liberals who don't accept that have forgotten the Quakers, who founded the abolitionist movement, to say nothing of The Rev. Martin Luther King. In fact, Democrats only win the White House when they nominate candidates like Jimmy Carter and Bill Clinton, who are familiar with Scripture and comfortable in church.

But religion as a guide or a beacon or an inspiration is one thing. Religion as the dominant credo or a blueprint for public policy can be a source of disastrous discord. John Danforth, a Missouri Republican who served three terms in the Senate, cites two congressional actions that demonstrate how his party has become "the political arm of conservative Christians."

One: Upholding President Bush's veto of a bill expanding Federal funding for stem-cell research. Two: Passing a measure barring Terri Schiavo's family from disconnecting her feeding tubes.

Those are precisely the kinds of issues (along with Iraq) that drove centrist, suburban Republicans to abandon their party and vote Democratic last year.

As an ordained Episcopal minister, Danforth has some credibility when he says: "At its best, religion can be a uniting influence, but in practice, nothing is more divisive."

Conservative Christians who refuse to make "compromises," who insist that abandoning the Republican Party is a way of "honoring Christ," profoundly misunderstand the American system. And if they help elect a Democrat, they get what they deserve.

Steve Roberts' latest book is "My Fathers' Houses: Memoir of a Family" (William Morrow, 2005). Steve and Cokie Roberts can be contacted by e-mail at stevecokie@gmail.com.