Q: Is it proper to call the perpetrators of the Sept. 11 terrorist attacks 'fundamentalists,' and, if so, are they similar in kind to Christian and Jewish fundamentalists?

A: Scholars say fundamentalism is an appropriate label to describe the belief system of the terrorists who attacked the World Trade Center and the Pentagon. But they make clear that there are two kinds of fundamentalism: one that is active, and one that is inactive.

Both groups share a passionate revulsion with the modern, secular world, which they see as seductive but also corrosive and corrupt. To them it is a world in which God and tradition have been expunged.

"The typical fundamentalist view is a wish to rescue the world from its own self," said Nancy Ammerman, a sociologist of religion at Hartford Seminary in Hartford, Conn.

Quiescent fundamentalists respond by fortifying their communities against the outside world and building walls that separate them from secular culture. Their co-religionists argue that the only appropriate response to the evils of modernity is a counterattack. This group of fundamentalists believes the best defense against secularism is an offense.

There are several examples of this kind of activist fundamentalism. Christians have killed doctors who perform abortions. Jews in Israel have thrown stones at cars driving on the Sabbath or have pushed for the expulsion of Arabs living in the Palestinian-controlled territories.

The extremist Muslims who undertook the Sept. 11 attacks were among the most sophisticated and savvy of fundamentalists, but scholars say their behavior fits a pattern. While extremists reject modern culture, they are often enamored with technological innovation and are willing to use it to the best effect -- whether that means building bombs, learning how to fly or, as is rumored, developing chemical and biological warfare.

"They're not peasants or astrophysicists," said R. Scott Appleby, a professor of history at the University of Notre Dame and an expert on fundamentalism. "Sociologists have found that the rank and file are drawn from technological and scientific fields, especially engineering."

Appleby said the activist fundamentalist approach to scriptures reflects their professional training. They read sacred texts as though they were blueprints or operational manuals and interpret passages in a highly calculated, literal way.

Finally, in their war against secular culture, activist fundamentalists tend to insist that the past offers the only true picture of proper religious devotion. Muslim fundamentalists have a vision of a past in which nations were ruled by a religious elite--preferably Muslim.

"There's a strong emphasis on a kind of golden age and a pure text undefiled by any human interpretation," Ammerman said. Sociologists say that in reality there never was a golden age when everyone was devout. History shows that religion is not fixed in stone like a monument. Its more like a river with many rivulets, changing over time.

Still, the impulse to glorify the past is strong.

"It's a myth, but it's a powerful myth," Ammerman said. "It's the way fundamentalists tell the story of the world."