Osama Bin Laden (second from left), in a video filmed in Afghanistan and released by Al Jazeera television on October 7, 2001. Photograph: Gamma-Rapho via Getty Images

Born in Virginia in 1970 to Palestinian-American parents from the West Bank, Nidal Malik Hasan joined the U.S. Army after high school and attended Virginia Tech and then the Uniformed Services University of the Health Sciences in Bethesda, Maryland, where he earned his medical degree. It was not his work as a psychiatrist that brought Hasan to public attention, however. On November 5, 2009, as he was about to be shipped overseas, Hasan began shooting everyone in sight at the Soldier Readiness Processing Center of Fort Hood, an army base 150 miles south of Dallas. When he had finished, 13 people lay dead and 30 more wounded. Hasan survived to face numerous charges of premeditated and attempted murder. His military trial has been set for March 5, 2012.

Like some other highly publicized instances of violence in the United States in recent years—the 2009 killing of 13 people at an immigration center in Binghamton, New York; the 2010 crash of a small plane into an Austin, Texas, office building by an antitax protester—the Hasan shootings can be viewed two ways, as the actions of a disturbed individual or as the work of a determined zealot. Seen one way, Hasan is not so different from the Columbine killers and the Beltway snipers and perhaps Jared Loughner, who was found incompetent to stand trial in the January 2011 attack on Representative Gabrielle Giffords in Arizona. These individuals, for reasons having more to do with a troubled personality than a particular cause, took advantage of the widespread availability of guns to call attention to their unhappy lives. With Hasan, however, a contrary narrative has been posited, one in which he symbolizes an association between Islam and violence. Viewed this way, he is like the men who brought down the World Trade Center, a Muslim radicalized by U.S. foreign policy who kills out of a twisted understanding of what his faith requires. Some mass killings are neither entirely personal nor entirely political, and the one carried out by Hasan seems to be among them.

The Fort Hood shooting prompted a national debate about its meaning. Although the New York Times op-ed columnist David Brooks shared the conviction that Hasan’s actions were tied up with his attraction to radical Islam, he directed his reflections toward us rather than toward him. Worried about appearing politically incorrect or engaging in religious bigotry, Americans, Brooks wrote, were far too attracted to psychological explanations for Hasan’s conduct. “We learned about pre-traumatic stress syndrome, and secondary stress disorder, which one gets from hearing about other people’s stress. We heard the theory . . . that Hasan was so traumatized by the thought of going into a combat zone that he decided to take a gun and create one of his own,” Brooks wrote. But excusing away cold-blooded, cause-motivated murder by invoking therapeutic categories, Brooks argued, is precisely the wrong way to understand what Hasan and his acts represent. Hasan chose his fate as he chose his faith. Psychologizing his motives served only to deny, “before the evidence was in,” Brooks said, “the possibility of evil.” This was not, he concluded, “the reaction of a morally or politically serious nation.”

Slobodan Milosevic, before an appearance in front of the International Criminal Tribunal for the former Yugoslavia, December 11, 2001. Photograph: Reuters/Corbis

So, what makes a nation morally or politically serious? For many who share Brooks’s position on the more conservative end of the political spectrum, the answer is clear: Americans were once a deeply religious people; at some point in the recent past, however—the 1960s are usually cited—they began to worship themselves more than their creator. Psychology and its emphasis on the self took the place of theology and its emphasis on the divine as a way of making sense of the world. Having rejected strict forms of religion in favor of a moral relativism uncomfortable with the language of sin and salvation, Americans, this way of thinking has it, now find themselves unprepared to take on those who are ruthlessly committed to achieving heaven’s perceived ends on earth. We should certainly regard such fanatics as evil. And no one can doubt that they are serious. We, by contrast, as Brooks described upper-middle-class Americans in his 2000 book, Bobos in Paradise, want to lead a life “of many options, but maybe not a life of do-or-die commitments, and maybe not a life that ever offers access to the profoundest truths, deepest emotions, or highest aspirations.” We are not a serious nation because we lack serious people with the capacity to recognize evil.

There is a good deal of truth in Brooks’s characterization of the American upper-middle class (and I say this not only because he relied on some of my sociological work documenting the non-judgmentalism he critiques). Still, the moral relativism about which he and I have been concerned cannot be quite as dominant as we have maintained. Six months after Brooks published his reflections on Bobos (his invented term for the bourgeois-bohemians of America’s new educated class), Americans elected George W. Bush president. Not long after that, Bush responded to the September 11, 2001, attacks by invoking the concept of evil as if it were a mantra. If the applause Bush received for his speeches is any indication, Americans seek to punish those who threaten them far more than they wish to empathize with them.

Along with Brooks and other conservatives, I believe that the experience of the 1960s did not prepare us well for the outbreak of political evil in subsequent decades. The tumult of the Age of Aquarius should have taught us that human beings are not simply free spirits who stand to benefit from loosening the constraints of faith and family. Who can forget Charles Manson or the Reverend Jim Jones? The years in which these cult leaders carried out their gruesome acts were in their own way a blissful age of innocence, producing exactly the kind of misguided idealism ill-equipped to stare down evil. Given what we know now, we would all have been better off reading Arthur Koestler’s 1940 novel Darkness at Noon than Charles Reich’s 1970 The Greening of America. Any nation fascinated by Hair and Jesus Christ Superstar is not one to be taken seriously.

I therefore took it as good news that, as the 20th century came to its awful conclusion, an impressive number of Western thinkers were in fact turning back to Koestler and his insightful exploration of the totalitarian temptation, as well as to intellectuals such as George Orwell, Ignazio Silone, Raymond Aron, Czeslaw Milosz, Simone Weil, Lionel Trilling, and Leszek Kolakowski, all of whom, whether religious or not, knew that Satan still walked among us. Confronting the string of horrors that began in Cambodia in the mid 1970s and culminated in the attacks of September 11, 2001, those writing under the guidance of Koestler and his soul mates were the thinkers most sensitive to the political evils of the day. It was an era that saw the publication of The Black Book of Communism, the 1997 accumulation of totalitarian horrors edited by the French historian Stéphane Courtois, and The Black Book of Bosnia, a 1996 compilation of articles from the circle writing for the New Republic documenting the monstrous deeds carried out in the Balkans. No one who read either black book could maintain that the writers who contributed to them failed to recognize the seriousness of the problem of evil, and the fact that the dream of a better world holds such a compelling attraction that some of the dreamers will determine to kill everyone who stands in the way of its realization.

Omar Hassan al-Bashir (center), arriving in the South Darfur town of Sabdo, Sudan, March 18, 2009. Photograph: Philip Dhil/epa/Corbis

Unfortunately for the question of national seriousness, however, if the 1960s failed to offer sufficient guidance for dealing with political evil, so too did the 1990s. We have for the past two or more decades witnessed enough cases of political evil to teach us that the age of moral clarity that followed the age of moral relativism has had problems of it own. We should have learned from the all too frequent failure of our responses to genocide and ethnic cleansing not to look back to the dark days of Nazi and Soviet aggression for models of understanding but rather to focus on causes local and contextual. It should have become apparent to us that, if it is correct to avoid the kind of grand, sweeping thinking that seductively leads to utopia, it is also essential to avoid grand, sweeping ideas about sin. The situation in Rwanda was genocide, but the conflict in Darfur grew out of an effort to put down an insurgency, and the difference matters. Political evil does not occur because we are too permissive, and it is not controlled when we become too strict. Koestler and those who thought like him, brilliant critics of one era, drawing their lessons from the great totalitarian movements of their time, turned out to be unreliable guides for another.

If anything, yesterday’s seriousness has become today’s shallowness. Because so many thinkers of our time continue to find the specter of totalitarianism in every outbreak of political violence in the contemporary world, the tough-minded awareness of the darker side of human nature so prominent in the decade or two before the 1960s has turned rigid, sectarian, and at times downright pathetic. It is not just that those who once exposed tyranny on the left have become indifferent to, if not apologists for, reactionary regimes on the right: No ideology has a monopoly on double standards. The calcification of political thought runs deeper than that. Political leaders whose speechifying insisted that Americans are an exceptional people, blessed by God to advance the cause of liberty, rushed to copy the ugliest methods of the totalitarian states that once were their enemies.

Thinkers who ask the West to appreciate the need for limited violence taught by the Judeo-Christian religions transformed themselves into advocates for endless war against the world’s only other major monotheistic faith. They have relied upon torture to coerce confessions. They have denied detainees, including those whose innocence is beyond doubt, the most basic legal rights. They have launched wars of aggression that have produced disproportionate damage among noncombatants. They have authorized other regimes to carry out their dirty work in secret. Their actions, it must be noted, generally have not resulted in anywhere near the number of deaths associated with those whom they fight against. But far from decreasing the political evil in the world, their decisions add to its total and inevitably corrupt liberal democracy’s respect for personal dignity and the law.

Those who once called for moral clarity became deeply implicated in moral confusion. The guidance they offer is more than wrong. When followed to its conclusions, as it was during the Bush years, it is downright dangerous.

The situation on the liberal side of the political spectrum is better, but not by much. When the violence in the former Yugoslavia and Rwanda exploded, there emerged among liberal intellectuals a new concern about the necessity for the West to intervene abroad in order to protect human rights. That consensus now stands in disarray. It took no time at all for born-again hawks to back the wrong war, as they did in Iraq, while their newfound sympathy for humanitarian intervention, as some of their leading advocates quickly came to realize, too often was received as outside meddling by those for whom it was intended.

Timothy McVeigh, outside the Noble County Courthouse in Perry, Oklahoma, April 21, 1995. Photograph: Ralf-Finn Hestoft/Corbis

Where political evil is concerned, America—indeed, the West in general—needs to become serious once more. Political evil is dualistic in nature: It relies on transcendental appeals nearly always associated with religious faith to then pursue carefully chosen strategic goals in the world of power and policy. Getting serious about political evil means responding to both the faces it shows us. We must never lose sight of the fact that political evil violates the central tenets of the West’s leading faiths as well as its most profound political philosophies. But we must also observe carefully the concrete conditions on the ground where it takes place, or is about to take place, if we are to limit its reach and control its consequences.

Responding effectively to political evil’s dual nature means overcoming the longstanding hostility between religious thinkers and those of a more secular bent. No one can take the problem of evil seriously without recognizing the contributions made by the world’s religious thinkers to evil’s persistence and power. It is not a question of converting to this or that faith, or even of believing in God. It is a question of drawing insight from prophets and believers who knew something about human imperfection. Evil is a problem for all, but especially for those who sing the praises of a beneficent God. If God is not and cannot be responsible for the evil we see everywhere around us, someone or something else must be. The search for that elusive cause is what gives theological reflection on the nature of evil its depth. Until very recent times, to be preoccupied with the problem of evil was to be obsessed with precisely where God’s plans for us went awry.

At the same time, political evil forces us into the secular terrain of nation-states and their drive for prestige and security. It thereby asks us to confront the insights of thinkers and policymakers who don’t have a theological bone in their bodies. Machiavelli is as important to understanding evil as Augustine or Luther. He may not have had much to say about the problem of theodicy, but he does have much to teach us about why power attracts, why nation-states pursue it, and what responses are required when the conflicts spurred by human greed spin out of control. Religion, in short, can help us understand that evil exists. Politics helps explain why it persists. Combining the two in appropriate ways offers the best method of avoiding the twin traps of bland indifference and overweening self-confidence that have bedeviled us so much in a world marked by terror, genocide, and ethnic cleansing.

Alan Wolfe is a professor of political science and the director of the Boisi Center for Religion and American Public Life at Boston College. This essay is drawn from his new book, Political Evil: What It Is and How to Combat It (copyright © 2011 by Alan Wolfe), by arrangement with Alfred A. Knopf, Random House.