Ingrid Mattson had given up God. She had stopped saying her rosaries, stopped taking Communion. She was an atheist, abroad in Paris the summer before her senior year of college.

But she could not stop listening to the Koran.

"Forget it," she told herself. "This can't be happening to me." Yet day after day, she popped the cassette into her Walkman, mesmerized by the chanting and oddly moved by lines such as: "The sun and the moon follow courses computed. And the herbs and the trees both bow in adoration... It is he who has spread out the earth for [his] creatures."

When she returned home to Canada after that summer of 1986, Mattson signed up for the only Arabic class she could find. It was full of 8-year-old immigrants, who soon came to resent her for winning so many of the chocolates the teacher awarded top students. Mattson wanted to enjoy hanging out in bars with her brothers, the way she always had. Instead, she found herself at her sewing machine, stitching head scarves. That spring, she gathered several Muslim friends as witnesses and pledged herself to Allah.

It was an unusual move for a white Canadian ex-Catholic. And it set Mattson down a trailblazing path.

About 60,000 Muslims in the U.S. and Canada recently elected Mattson, 43, president of the largest Muslim organization on the continent, an educational and professional association called the Islamic Society of North America. She is the first woman, nonimmigrant or convert to Islam to become president of the group.

Her election comes at a tumultuous time for the estimated 6 million Muslims in the U.S. Nearly 40% of Americans admit prejudice against Muslims, according to a recent poll by USA Today and Gallup. A similar percentage support mandatory identification cards for Muslims. And one in five Americans said they would not want a Muslim neighbor.

Many Muslims are hoping Mattson can soften this fear. She does not speak with a foreign accent. She doesn't wear a veil, though she does cover her head with a thick, dark scarf. Soft-spoken and quick to smile, Mattson is a suburban soccer mom; she cheers at her son's games, helps her daughter with college applications, gardens, hikes, reads the New Yorker, laughs at Paris Hilton's reality TV.

"Many Americans think we didn't arrive in this country until 9/11. She helps people know we're part of the American landscape," said Aneesah Nadir, the president of an Islamic social services agency based in Phoenix.

Such comments were a frequent refrain at the Islamic society's annual convention, which drew more than 32,000 Muslims to this suburb of Chicago earlier this month. Mattson was mobbed by fans wanting to take her picture. One father brought his five daughters from South Carolina to meet her. "She's a visible refutation of stereotypes," said Hasan Aijaz, a college student from Virginia.

Outside the organization, Muslims have greeted Mattson's election more warily.

She's received angry letters from conservatives who resent having a woman in charge. Such critics often cite an ancient hadith, or narrative about the life of the prophet Muhammad, stating that no good will come from entrusting leadership to a woman.

The Islamic left has questioned Mattson's credentials as well. A traditionalist who dresses in modest ankle-length skirts and loose blouses - and who prefers, whenever possible, to avoid shaking men's hands - Mattson pushes women's rights only so far.

She has called for mosques to dismantle any barriers that block women from seeing or clearly hearing the imam during prayer. But she does not support the more radical, feminist notion that women should pray alongside men - or even lead men in prayer. Many Muslims argue that such an arrangement would distract men from God or lead to immoral conduct. Mattson explains her objection this way: The prophet would not have approved.

Mattson's journey to Islam began when she was a teenager in the Canadian town of Kitchener, Ontario. As a girl, she had been the most pious in her family of seven children, but when she entered high school, she began to find bedrock concepts such as the Holy Trinity illogical. The nuns and priests at her Catholic school were unable to answer her questions. "Accept the mystery," they told her. She couldn't.

Though she stayed on at St. Mary's High School, Mattson stopped looking for God.

Years later, during her summer in Paris, Mattson became friendly with several West African Muslims. They introduced her to Islam; her spirit stirred. "What moved me most was the way the Koran described the majesty and beauty of creation," she said.

One of her favorite passages tells of God's handiwork: "He has let free the two bodies of flowing water, meeting together... Out of them come pearls and coral... And his are the ships sailing smoothly through the seas, lofty as mountains."

After graduating from the University of Waterloo, Mattson worked in a refugee camp in Pakistan, where she met her husband, an Egyptian engineer. He took care of their small children while she earned a doctorate in Islamic studies from the University of Chicago. Since 1998, she has been teaching about Islam at Hartford Seminary, a nondenominational Christian institution in Connecticut.

As president of the Islamic Society of North America - an unpaid part-time post - Mattson will lead a diverse organization that trains Muslim leaders, sets standards for hundreds of mosques, helps immigrants adjust to American life and serves as an umbrella uniting associations of Muslim engineers, doctors and other professionals.

She will also be a very visible spokeswoman for the faith - a role she relishes. In particular, she can't wait to refute the notion that Islam is a religion solely "for brown and black people," she said.

"When African Americans make the move to Islam, it's considered valid. When I do, it's considered cultural apostasy, as if somehow I've abandoned my whiteness to become an 'other,' " Mattson said.

In the past, many Muslims - like evangelical Christians before them - argued that they had to isolate themselves from American politics and culture in order to keep their faith pure. In the aftermath of Sept. 11, Mattson argues that Muslims no longer have that luxury.

"We need to form an axis of good with our neighbors," she said. "We're 2% of the American population. How are we going to be effective unless we make alliances?"

Her push for interfaith partnerships got off to a shaky start when the Islamic society invited former Iranian President Mohammad Khatami to address the convention. Jay Tcath, vice president of the Chicago Jewish Federation, accused the organization of "a dereliction of civic responsibility" for honoring Khatami despite his record of human rights abuses.

The Anti-Defamation League also takes issue with the Islamic society for having provided a forum for anti-Semitic language at several conferences over the years, said Deborah Lauter, the group's national civil rights director. The organization's leaders "have been in bed with extremist groups," Lauter said, "[so] we go into these relationships with some serious concerns."

Mattson says her group does not invite speakers "known for offensive statements," but offers "as broad a platform as possible for legitimate views." At the convention's opening seminar, Mattson urged her fellow Muslims to step proudly into mainstream society, to engage their neighbors and promote their good works until Americans stop associating Islam with terror.

"Islamic medical clinics... Islamic ethics. Islamic charity. These are the terms that should come off the tips of tongues," she told a cheering crowd. "Islamic intellectuals. Islamic peace movements. Islamic human rights... This is who we are!"

Stephanie Simon is Times Staff Writer and can be reached at [email protected]