"These are times in which we could literally change the world by the spread of freedom," President Bush told supporters last week at a Wisconsin rally. "Freedom is not America's gift to the world; freedom is the Almighty God's gift to each man and woman in this world." In such declarations -- and they are frequent from Mr. Bush -- critics see a "messianic militarist" at work, to borrow a phase from Ralph Nader.

By historical standards, however, Mr. Bush's political ideals are in the mainstream of presidential rhetoric. Every U.S. president, Democrat and Republican, has upheld the sacred dignity of the individual as an essential tenet of the nation's political creed. Even John Kennedy, who famously denied that his Catholic faith would influence his politics, denounced communism by asserting that "the rights of man come not from the generosity of the state, but from the hand of God."

What is more, past presidents have regarded the promotion of democratic values as America's supreme obligation in the world -- and a mission consistent with the will of God. "America is privileged to spend her blood and her might for the principles that gave her birth and happiness and the peace which she has treasured," Woodrow Wilson told an emergency session of Congress in 1917. "God helping her, she can do no other."

At the start of the Cold War, Harry Truman pledged to support any nation struggling against totalitarian aggression. "Steadfast in our faith in the Almighty," he said, "we will advance toward a world where man's freedom is secure."

When President Bush talks this way, he is pilloried as a faith-based imperialist. Likewise, his blunt assessment of the terrorist threat -- the "axis of evil" -- is considered the product of a dangerously naïve theology. Jim Wallis, the editor of the liberal journal Sojourners, complains that Mr. Bush's brand of religion sees only the evils of its enemies and "rules out self-reflection and correction."

What political leader, however, braces Americans for a bloody conflict by lamenting the nation's social and political sins? None who faced the most perverse dictatorships of the 20th century. "We are fighting to cleanse the world of ancient evils, ancient ills," intoned Franklin Roosevelt during World War II. "There never has been -- there never can be -- successful compromise between good and evil." Was FDR, the icon of modern liberalism, actually a closet evangelical?

Follow the logic of Mr. Bush's detractors, and most of the country's leaders look like messianic zealots. Calvin Coolidge, who approved the 1928 Pact of Paris, a quixotic attempt to persuade nations to renounce war, saw a divine role for the U.S. in such a peace-keeping mission. "America seeks no earthly empire built on blood and force," he said. "The legions which she sends forth are armed, not with the sword, but with the cross."

Dwight Eisenhower, known for his modest attachment to "religion in general," would be savaged today for describing the Cold War in biblical terms. "We sense with all our faculties that forces of good and evil are massed and armed and opposed as rarely before in history," he said in 1953. "Destiny has laid upon our country the responsibility of the free world's leadership." Ronald Reagan, of course, was mocked for calling the Soviet Union an "evil empire" -- exactly what those who suffered under its rule knew it to be.

There are, to be sure, serious pitfalls in identifying foreign policy with divine will. One of the great strengths of American democracy is its capacity for self-criticism, a virtue that gets put in cold storage in the heat of a holy crusade. Religious intuition, after all, is no substitute for sound judgment: We don't mind seeing a president on his knees, but he'd better be on his feet as well, engaged with the wisest mortals available -- listening, debating, and thinking about the rightness and wisdom of his cause. The Iraq prison scandal surely taints Mr. Bush's democracy-building agenda. But nothing in his theology has stopped him from demanding a "full accounting for the cruel and disgraceful abuse" of detainees at Abu Ghraib.

Nazism and communism confronted American presidents with profoundly malignant, secular ideologies. In a similar way, the attacks of 9/11 thrust upon Mr. Bush the reality of a malevolent Islamic radicalism. In each case the language of the materialist seems unfit to address the evil of the hour; in each case our leaders turn instinctively to religious ideals. "As we meet the terror and violence of the world," Mr. Bush told an audience last November, "we can be certain the author of freedom is not indifferent to the fate of freedom."

Is it hubris to talk this way? Perhaps, but most Americans don't live in an existentialist universe; they believe in moral truths, embedded in human nature and validated by nature's God. This is the touchstone of America's democratic faith. The nation's leaders have sometimes failed miserably to advance this vision of freedom in the world, but it's important to ask what the world would be like without it.

Mr. Loconte is a fellow at the Heritage Foundation and editor of the forthcoming "The End of Illusions: America's Churches and Hitler's Gathering Storm."