Right up to the moment President Bush issued his ultimatum to Saddam Hussein, war opponents insisted that peaceful means to disarm the Iraqi dictator had not run their course. Religious critics claim the crucial test for a "just war" -- that it be used as a last resort -- hasn't been met. But it's the distortion of just-war doctrine that helped delay action against Baghdad and create the current crisis.

The mischief began at least 20 years ago, when the U.S. Catholic bishops issued "The Challenge of Peace," a pastoral letter redefining the litmus test for war. Not only must military action be a last resort, they said, but "all peaceful alternatives must have been exhausted."

In recent weeks, that slippery phrase reappeared -- and muddied the entire debate over Iraq. The Vatican issued a cryptic, one-line rebuttal to war plans: "Those who decide that all peaceful means that international law makes available are exhausted assume a grave responsibility before God, their conscience, and history."

The American bishops have repeatedly invoked the new standard to denounce a U.S.-led attack. So has the National Council of Churches, demanding that all peaceful alternatives be "explored and exhausted." In a New York Times op-ed, former President Jimmy Carter used the expression like a club to bludgeon the military option. "War can be waged only as a last resort," he wrote, "with all nonviolent options exhausted." U.N. Secretary-General Kofi Annan says war is acceptable "only if we are sure that every peaceful means of achieving Iraq's disarmament has been exhausted."

Yet there is nothing like this standard in traditional just-war theory, not as formulated by Augustine, or expanded upon by Thomas Aquinas. Small wonder: When the maxim is actually applied, such as during the outbreak of hostilities in Kosovo or Rwanda, it becomes a cover for paralysis. Crises that require serious moral judgments, backed up by swift and lethal force, receive neither. In Rwanda, the United Nations stood by as mindless bloodletting claimed upwards of 800,000 lives. But at least religious leaders were satisfied that their doctrine had been upheld.

One becomes exhausted contemplating what the "exhaustion" of peaceful options might mean. Does it involve tighter economic sanctions, a beefed-up inspections regime, an extension of the no-fly zones, the issuing of more U.N. resolutions? All of these strategies have been tried with Iraq -- but not, according to war critics, to the point of exhaustion.

After all, they say, we must have evidence of an "imminent attack" against the United States. Yet this view of aggression is closer to the fifth century, in which just-war theory was formulated, than the era of nihilistic rage in which we now live. The new reality is the horrific link between terrorist organizations, rogue states and weapons of mass destruction. According to the latest CNN poll, 85 percent of Americans believe that Iraq belongs in this demonic inner ring.

Can America respond with force only when an Iraqi missile carrying a chemical weapon is seconds from lift-off? Or only after Saddam has slipped a few liters of anthrax into the hands of al-Qaeda allies? If there ever was a time when theology must be "updated" to reflect contemporary facts, this is it.

Even now, disciples of the School of Exhaustive Diplomacy refuse to make a final judgment about the basic character -- and predictable behavior -- of a tyrannical regime. They ignore evidence of Saddam Hussein's intractable evil: his state-backed megalomania, unprovoked wars of aggression, use of chemical weapons against the Kurds, the expulsion of weapons inspectors, attacks on U.S. aircraft, support for terrorist organizations, and defiance of 17 U.N. resolutions since his defeat in the Gulf War.

Saddam has long been prepared to subject his people to a devastating war for one purpose: to extend his power by developing and deploying the world's deadliest weapons. Only the marshalling of 250,000 American and British troops on his border interrupted that pursuit. And only the most naïve moralists could fail to admit its implications.

Just-war doctrine remains essential to international order, but if it can't sanction action against this menace, it needs revision. Grounded in Christian ethics, the theory guards against warmongering in the pursuit of national security. But when all peaceful alternatives to war have failed, the doctrine must not become a suicide pact with civilization.

Originally appeared on National Review Online and is running on the Knight Ridder wire.

- Joseph Loconte is the William E. Simon Fellow in Religion and a Free Society at the Heritage Foundation and a commentator for National Public Radio.