The horrendous events of September 11 confront us with a reality even more disturbing than our apparent vulnerability to terrorist attacks. They require us to reexamine our entire understanding of the nature of reality.

In the face of unimaginable catastrophe there has been much talk about tragedy, human suffering, heroism, cowardice, patriotism, and resisting hatred, all of which are true as far as they go.

But events now confront us with realities so enormous that little can be said, and our culture's ultimate failure is that it actively works against the ability to understand such things. As most Westerners view reality, there is no reason why such things should happen. Thus, it seems that those who perpetrate such acts have simply made certain mistakes of understanding, reinforced by excessive emotion. Terrorism, we are told, solves nothing. The terrorists' grievances are understandable, but they have chosen the wrong methods.

For some people, the whole episode revolves around technical problems – better security systems, the necessity henceforth to be more vigilant, in ways other peoples simply take for granted. For others, the solution is retaliation against the terrorists, followed by diplomatic efforts to "get to the root of the problem." What these have in common is the assumption that what we face is containable and comprehensible within the categories of understanding that our culture permits.

People turn to religion at such moments, but even the most devout realize the limits of the comfort that the faith provides for bereaved people. Christianity offers no "answer" to the questions, no coherent resolution of all perplexities. Rather, it speaks of the "mystery of iniquity." The common religious responses are not wrong - comfort for the bereaved, the promise of resurrection, a righteous desire for justice, love of enemies. But none of these explain "why." Rather, our faith opens us to the eternal and cosmic perspective.

This is not only our belief that the dead still live in Christ, which provides comfort and meaning in a way no purely worldly creed can equal. It means rather that our faith makes us understand that events of this kind are not merely bizarre anomalies. We are engaged, as we always have been, in a war against principalities and powers, something we can forget only because of the numerous comforts our culture provides.

Despite our Puritan heritage, most Americans simply do not believe in evil. They prefer to believe in "mistakes," "failure to grow," "misguided zeal," "social causes," "lack of empathy for others," and similar rationalizations. We apply those ideas routinely to our own lives; thus, we see the cosmic picture in the same way.

The two common explanations of terrorism are a sense of injustice and religious fanaticism, and both are real enough.

Predictably, fanaticism will be used to argue that religious belief is a dangerous thing, the source of many of the world's evils, and there is a point to that claim, albeit not the one that its proponents make. Precisely because religion does put us in touch with the deepest wellsprings of existence, it has the greatest potential for both good and evil. A religionless world, whatever else it might be, would be a spiritually impoverished world. Religion is indeed a volatile substance, precisely because it is the realm where good and evil directly meet.

The "problem of evil" is insoluble even for Christians, because finally we do not know why the all-good God permits evil, although our greatest glory - our freedom - is also the instrument by which we thwart the divine will.

Since God cannot create evil, Christianity defines evil as nothingness, the absence of being, as St. Thomas Aquinas calls it. At first, this may seem specious, but the events of September 11 show quite dramatically that it is so. The essence of the terrorist act is to reduce being to nothingness. Before our very eyes, some of the most imposing monuments of our prosperous society are reduced to dust, even as thousands of human beings cease to exist in this world. The essence of all evil is to make something into nothing. The climax of the latest terrorist acts was the willful annihilation of the terrorists' own selves, the ultimate act of allegiance to nothingness.

For motives we find difficult to understand, this urge to annihilate has a powerful fascination. Thus, if the apparent causes of terrorism were removed, things of this kind would still occur, because they are rooted in human nature gone awry. Political and religious grievances provide the rationale for such actions, but such things happen every day on the personal level.

Religion has to do with ultimate reality. God, St. Thomas tells us, is pure being, the fullness of existence. But Satan is a fallen angel whose own limitations nurture a horrifying hatred of all that is good, a hatred of being itself. The power of evil is the power of a vacuum - a nothingness that sucks everything into itself in order to destroy.

The events of September 11 also have inevitably brought into focus the various ways in which our culture teaches people to evade recognition of evil.

Some, predictably, recognize it but see it in the victims. They issue long lists of conditions that the United States must fulfill before it can even begin to ask for justice. But in the minds of such people, America is the cause of most of the evil in the world, so the list will never be complete.

A variant convenient way of avoiding confrontation with evil is the positing of moral equivalency - the claim that an act of such magnitude must have been provoked by some equal injustice. Why else would anyone do such a thing?

A leading guru of the New Age movement gave a presentation in which he talked about - himself. He had, he confessed, discovered violent feelings even within himself. Fortunately, this gave him the opportunity to take his listeners through a meditation exercise guaranteed to eradicate those feelings. His claim was intriguing because of its incorrigible self-centeredness - the guru foreswore all thoughts of vengeance by pretending that the universe is contained within his own head.

A student leader smiled cheerfully on television as she said, "I'm really proud of the way this has been a real growth experience for most students," as though the havoc were worthwhile because of the challenges it offered.

Among some religious believers, evasion took the familiar form of treating evil as a mere personal inadequacy, to be overcome by sincere effort. Thus, we were solemnly exhorted to cultivate peaceful attitudes and to "reach out" to others, who would then reciprocate, without even a clue as to why, realistically, attitudes of peacefulness on our part will lead to a change of heart by our enemies.

On the eve of World War II the most influential American theologian of the twentieth century, Reinhold Niebuhr, broke with many of his fellow liberal Protestants because of their lack of realism, their inability to recognize the menacing evil that then confronted civilization.­

On one level, their failure might have been dismissed as pious sentimentality. But Niebuhr understood that it made otherwise good people into apologists for evil, so eager were they to avoid confrontation with it. It was also another manifestation of self-centeredness - projecting onto others, who live thousands of miles away both geographically and culturally, our own fondest beliefs.

Crises are a basic test of religion, and our religion passes that test, as shown by the many people who spontaneously turned to faith during the latest crisis. But some spokesmen for religion in fact make it irrelevant, implying that being a believer means dreaming about the world as we would like it to be, the sort of escapism that religion's critics have always charged it with.

Sentimental people persist in seeing a peaceful world just around the corner, so that when events like those of September 11 occur, they react like a man convinced that one more round of tinkering with his backyard invention will at last produce a working perpetual-motion machine.

The blunt truth is that Christianity teaches us that we will never, short of the end of time, achieve a world of perfect peace and justice. That does not mean that we are absolved from working towards it, nor that in certain periods we might seem closer to it than at others. But the perfect society will never come. That is what Original Sin means.

Those who deny that religion has anything to do with terrorism miss the point. No doubt such terrorism is a perversion of the highest teachings of Islam. But all religions, including Christianity, contain things that are available for such perversion. Those who kill in the name of religion are seldom merely using it as an excuse. Usually, they are believers whose sinfulness leads them to turn good into evil.

Perhaps the ultimate evasion is the assumption that the events of September 11 are so extreme that they manifest an exotic reality that need only concern us in times of emergency. But to think that is to miss the most basic reality. Deliberate mass murder is unique only in its magnitude, the events of September 11 unique only in the dramatic way in which they manifested evil. The somber truth is that actions of this kind go on all the time.

There was a startling report by a terrorism expert that each year about 30 pilots deliberately crash their small planes in an attempt to kill themselves and someone they hate-an ex-spouse, a former employer. "Serial killers," who kill only for their own gratification, are a recognized category in our society, and every day there are numerous malicious assaults on essentially innocent people. Such things are not, of course, the whole story of human nature, bur they are a necessary part of it.

The idea of moral equivalency is attractive because it seems to lessen evil - terrorism occurs only because of injustices done to the terrorists. But believing that requires believing that every violent act, anywhere at any time, must have understandable motives. It ignores the reality of irrational hatred, of malice.

It is in recognizing this that religion begins to show its ultimate relevance. Believing in evil does not automatically dictate any particular course of action in any particular situation. But it ought to be the first condition for anyone claiming to have something to say about terrorism.