In his speech marking the fifth anniversary of the 9/11 attacks, President Bush accurately described our nation's ongoing war against the people who attacked us as "the decisive ideological struggle of the 21st century." This war is a struggle for our civilization. I have spent a lot of time talking about the formidable enemy we face because I do not think many Americans understand the high cost of losing this war.

The ideology we are fighting is not terror; terrorism is only a tactic. The ideology we fight is Islamic fascism. Islamic fascists are the heirs to the Nazis and others we fought in World War II. The foot soldiers of this worldwide jihadist movement subscribe to a radical, perverted form of Islam, and they seek to dominate or destroy the United States and freedom-loving people everywhere. Every major Islamic fascist leader promises the creation of a new, global "caliphate" to rule all peoples. This message comes from radical Sunnis and Shiites alike, whether Arab, Persian, Indonesian, American, or British.

Al-Qaeda and other Islamic fascists have been attacking U.S. targets for decades, because we stand in the way of their goal to subject the world to their tyrannical rule. The 9/11 attackers used airplanes, Hezbollah uses katyusha rockets, and Iran's dictator is eyeing nuclear weapons; but they are one and the same enemy, and their principal weapon is fear. Beyond Iraq and Afghanistan, they have expanded their presence to nearly every continent. They even have invaded the Americas through Iran's ties to the Cuban and Venezuelan dictatorships.

This is a war of attrition, and we either fight the fascists or perish. They are a dangerous enemy with an ideology that motivates people, and they have a tactic that is uniquely effective. The terrorist tactic is to cause death every day -- not to defeat the military, or drive back the lines of our troops, or control additional territory. Every day in this psychological war they wage, they want to make it harder for Americans to read the newspaper or turn on the television and see more death.

As Osama bin Laden said, "We will defeat you because you love life; we love death." They love death because they see death as better than life. They are willing to die; they want to die. Islamic fascists want a nuclear weapon in Iran -- not to stave off attacks, but to pursue their messianic vision of the return of the twelfth, or Hidden, Imam. They believe it is their obligation to bring about the end of time by the destruction of the state of Israel and by world chaos in which Islam suppresses the infidels. Only then will the Hidden Imam return, fulfilling that prophesy.

Some say we should not speak about Islamic fascists because we might offend Muslims. I say remaining silent is the real offense to Muslims. Moderate Muslims need to publicly reject this virulent strain of Islam that spreads fear and fuels a bloody war. Islamic fascism produces the systematic murder of innocents, including many Muslim innocents. Furthermore, speaking against this destructive ideology is crucial to the cause of religious freedom. If the enemy wins this war, only Muslims will be able to practice their religion.

The president is right: This is our hour to lead by promoting the only possible antidote to radical Islam in the Middle East -- democracy. As leading Middle East historian Bernard Lewis says, "We free them or they destroy us."

We can seek political advantage to win the next election, or we can confront the reality of this hour and fight Islamic fascism. On my watch, even though I am facing a challenging reelection campaign in Pennsylvania, I am going to confront this threat. Islamic fascism threatens our civilization, and I pray we have the courage to defeat it.