We do not know precisely at this point what military and other responses are being planned after to the attack of Sept. 11, and therefore can make no judgment as to whether they are feasible, prudent, or just.

We do know some things for certain, however.

We know the first obligation of government is the well-being of its citizens, and that protection is essential to well-being. And there is a duty of justice to punish the aggressor. There is a necessary connection between punishment and protection. We punish in order to do justice, and we punish in order to deter and prevent, and thereby protect.

The traditional criteria of morally justified war, usually understood to apply to conflicts between sovereign states, apply also here. An international terrorist network may be seen as a kind of shadow state, probably operating with the assistance of recognized states.

It is also worth remembering that in St. Augustine, for instance, war may be justly waged against brigands and gangsters who do not constitute a state. Although it rubs against prevailing sentiment, just war in response to aggression can also be an act of love. In the Summa Theologiae (II-II.40), Thomas Aquinas discusses just war not in the section on justice but in the section on love.

Just war, aimed at establishing just peace, is the mandatory course of charity. But was Sept. 11 an act of war or simply a horrendous crime?

Those suspected of perpetrating the act have for years made no secret of the fact that they believe they are at war with America and, if they are the guilty parties, they certainly intended it as an act of war. The United States has declared it to be an act of war. We are rightly reminded that this is not a war against Islam but against the diseased mix of religion and utopian ideology called radical Islam or, more accurately, Islamism.

At the same time, the West is now being compelled to recognize itself more clearly for what most Muslims perceive it to be — the Christian West, or Christendom. We cannot understand Sept. 11 unless we understand it as a part of a history that goes back to the seventh century; the Islamic conquest of northern Africa and Spain, the Christian efforts at reconquest (commonly called the Crusades), and up through Islam's more recent centuries of colonial rule by the West and much resented exclusion from the challenges and benefits of modernity.

While refusing to cast this latest phase of that history as a war of religions, everyone is now forced to appreciate more fully the prescient arguments of Harvard's Samuel Huntington regarding a “clash of civilizations.” The current conflict is part of a very long story, and we must brace ourselves for the likelihood that it will be a very long time before it is resolved, if it is resolved.

Sept. 11 recalled America from an extended and mainly hedonistic holiday from history. Pray that we have the courage, endurance and wisdom to pursue a course of justice and love worthy of the civilization that is ours.

Father Richard John Neuhaus is editor in chief of First Things magazine

In New York, a publication of the Institute on Religion in Public Life.