But bin Laden and some other terrorists say the less militant parts of Muslim teachings simply don't apply to their war with the West. This belief can be traced to a few well-known figures of relatively recent Muslim history.

Muhammad ibn `Abd al-Wahhab was a contemporary of George Washington. His supporters say he was a religious reformer who cleaned up a corrupted version of Islam practiced in his part of Arabia. Opponents call him a political opportunist who used religion as a weapon. In either case, he declared that Islam had been corrupted a generation or so after the death of Mohammed, and he condemned any theology, customs or practices developed after that.

It was as if a Christian suggested that Augustine and Aquinas and every later Christian theologian was a heretic. Or as if an Orthodox Jewish scholar challenged the validity of the Talmud.

Al-Wahhab and his supporters took over what is now Saudi Arabia. Their descendents still control the area and are among the most influential religious leaders in much of the Middle East.

Sayyid Qutb, an Egyptian Muslim radical from the mid-20th century, is another important influence. Qutb lived in the United States for several years and declared all of Western civilization the enemy of Islam. In fact, he declared leaders of Muslim nations enemies for not following Islam closely enough. Like the followers of Wahhab, Qutb shoved aside most of Muslim religious historical thought, said Bill Shepard, a retired professor of philosophy and religious studies at the University of Canturbury in New Zealand who has extensively studied Qutb's history.

"He was one of the first Islamist writers to target the United States as the enemy," he said.

After the Egyptian government executed Qutb in 1966, his followers formed the violent Muslim Brotherhood and were responsible for the assassination of Egyptian President Anwar Sadat.

The Taliban, the rulers of Afghanistan who have sheltered bin Laden for several years, follow a religious pattern similar to his. Like the followers of al-Wahhab and Qutb, they reject much of historic Muslim thought and insist that their interpretation of Islam is the only correct one.

Followers of al-Wahhab and Qutb might have remained relatively obscure but for an accident of geography and economics, said el Fadl of UCLA. When the price of oil soared in the mid-1970s, some believers in a narrow version of Islam suddenly had the wealth to disseminate their point of view. Some used their money to build schools and mosques. Bin Laden, scion of a billionaire, chose to spend his millions in other ways.

"Oil is easy money," el Fadl said. "You put easy money with an easy ideology and you have an explosive combination."