THE RECENT WAVE of church bombings, kidnappings, and executions of civilians in Iraq seems to support a contested claim by the Bush administration: that radical Islam is the philosophical cousin to European fascism; that it has less to do with politics than with nihilistic rage. As Bush put it in his address to Congress barely a week after the 9/11 attacks, "By sacrificing human life to serve their radical visions--by abandoning every value except the will to power--they follow in the path of fascism, and Nazism, and totalitarianism." The president has asserted an Islamist-fascist link in at least a dozen speeches over the last three years.

Critics assail this argument as dangerously "ideological"--there's too much moralizing about the evil of terrorism, they say, and not enough curiosity about the "root causes" of Islamic violence. Religious liberals such as Bob Edgar of the National Council of Churches deride Bush's moral vocabulary as a way of "dehumanizing" America's enemies. Writing recently in the New York Times Book Review, political scientist Ronald Steel scolds administration hawks for ignoring "the essentially political causes of terrorism."

The eyewitnesses to Nazi terrorism, however, might well take exception to that view. Eric Voegelin, whose 1938 book The Political Religions made him a target of the Third Reich, offers perhaps the best-known critique of the moral and spiritual rationalizations of fascist ideology. A short work published in 1939 by philosopher Lewis Mumford, however, is also worth revisiting. Titled Men Must Act, the book grew out of Mumford's visit to Germany in the early 1930s. There he saw copies of Mein Kampf ("my struggle," Hitler's autobiography and political manifesto published in 1926) being snatched up in bookstores. He watched how Nazi brownshirts had taken over the streets in Lübeck, and listened at dinner parties as upper-class Germans praised Hitler's program against the Jews.

Writing when America was still in a pacifist mood, Mumford aimed to prod U.S. support for the Allied cause. His summary of fascist principles reads today like a recruiting manual for the al Qaeda network: (1) the glorification of war, (2) a hatred for democracy, (3) a hatred for civilization, (4) a contempt for science and objectivity, and (5) a delight in physical cruelty.

The sadism and irrationality of fascism have long been favorite themes among scholars, but many in America came under the spell of its pseudo-scientific arguments. Bigotry was part of the reason: From 1933 to 1941, over a hundred anti-Semitic groups appeared in the United States, many of them with a Christian hue. Some of Mumford's close friends turned against him when he argued that Nazi claims rested on racist, conspiratorial delusions. "What the leader desires is real: what he believes is true: what he anathematizes is heresy," he wrote. "These fiat truths bring about a debasement of the entire intellectual currency."

How does that compare to Islamic radicalism?

The writings and statements of Osama bin Laden, and those of his philosophical mentor, Sayyid Qutb, point to the true nature of their grievances. The object of their hatred is not merely "international Jewry"--the Nazi slogan--but all "infidels," in particular the "Zionist-crusader alliance." The terrorist attacks in Iraq show that the enemies of al Qaeda include citizens not only of the United States, but of Jordan, Saudi Arabia, Pakistan, Kuwait, Kenya, India, Bulgaria, South Korea, and the Philippines. They may be politicians, police, factory employees, doctors, relief workers--anyone supporting a decent civil society. They include not only Christians and Jews, but dissenting Muslims. Here, then, is an ideology that reviles anyone who upholds the moral norms of civilized states. As Christopher Hitchens has aptly phrased it, here is "fascism with an Islamic face."

ONE OF THE FIRST religious figures in America to grasp the threat of German fascism was Stephen Wise, president of the World Jewish Congress. As early as 1933, when Hitler came to power, Wise was warning that Nazism challenged "the conscience of humanity" with its treatment of Jews and other non-Aryans. He insisted that Hitler be judged not only by his military aggression, but by the viciousness of his anti-Semitism--a campaign to shatter the foundations of every democratic society. "Peoples and churches permitted themselves to be lulled into unawareness, because it was only or chiefly the Jew who at the outset was hurt," Wise observed in 1938. "Men heeded not that the Jews were assailed as symbol of that civilization, the values of which Nazism was resolved to destroy."

Mumford similarly faulted America's political and religious leaders for excusing "the true stigmata of fascism," its love of sadistic violence. The roots of this pathology had little to do with political or economic grievances, as many assumed at the time. Rather, the Nazi obsession with violence and war was self-generated--and insatiable. It produced a regime in which blackmail, repression, and terror were not accidental injustices, but part of the very structure of the state.

"We had glibly assumed," Mumford wrote, "that barbarism was a condition that civilized man had left permanently behind him." The Nazis refuted all those assumptions, and no appeals to reason or diplomacy would deter them. Indeed, although a secular thinker, Mumford came to believe in "radical evil"--that savagery is the easy way for mankind, the natural drift of things apart from some restraining force or grace. That insight is worth bearing in mind in light of the 9/11 Commission report. Its authors complain of a "failure of imagination" in the face of terrorist threats, but it's still not clear that Washington's policy elites appreciate the religious nihilism that sustains radical Islam.

In his recent book The Third Reich, historian Michael Burleigh argues that Hitler's Germany clung to a Teutonic myth of heroic doom, a high-stakes war for national and racial restoration--or perdition. The ideology of Nazism, he writes, "offered redemption from a national ontological crisis, to which it was attracted like a predatory shark to blood."

Today, it seems, the predators have returned. The crisis this time is not national and race-based, but supranational and faith-based. The stakes are equally high, the methods as thoroughly wicked: videotaped beheadings, the mutilation and public parade of corpses, the murder of women and children, the recruitment of boys for suicide missions. "We must keep in mind the nature of the enemy," President Bush told graduates at the U.S. Air Force Academy in June. "No act of America explains terrorist violence, and no concession of America could appease it."

Some reject that argument--such as the governments of Spain and the Philippines, which have bowed to terrorist demands to pull their troops out of Iraq. Yet the early warnings about Nazism seem eerily relevant today. "What will finally emerge, if fascism continues to prevail in Europe, will be a system of barbarism: its stunted, emasculated minds: its grandiose emptiness: its formalized savagery," Mumford wrote. "The relapse into barbarism is a recurrent temptation. Only men can resist it."

Joseph Loconte is the William E. Simon fellow in religion at the Heritage Foundation and editor of the forthcoming The End of Illusions: Religious Leaders Confront Hitler's Gathering Storm.