During the months I spent in the insular world of young American Salafis, it became clear how pressing those questions are for many conservative Muslims who have come of age after 9/11. They have watched as their own country wages war in Muslim lands, bearing witness — via satellite television and the Internet — to the carnage in Iraq, the drone attacks in Pakistan and the treatment of detainees at Guantánamo. While the dozens of AlMaghrib students I interviewed condemned the tactics of militant groups, many share their basic grievances. They are searching for the correct Islamic response, turning to the ancient texts that guide their American lives. Their salvation, they say, hangs in the balance.

This is what makes Qadhi such a pivotal figure in a subculture that is little understood, even by the law-enforcement officials who monitor it. He is the rare Western cleric fluent in the language of militants, having spent nearly a decade studying Islam in Saudi Arabia, steeped in the same tradition that spawned Osama bin Laden’s splinter movement. Arguably few American theologians are better positioned to offer an authoritative rebuttal of extremist ideology. But to do that, Qadhi says he would need to address the thorny question of what kinds of militant actions are permitted by Islamic law. It is a forbidden topic for most American clerics, who even refrain from criticizing their country’s foreign policy for fear of being branded unpatriotic.

For an ultraconservative cleric like Qadhi, the picture is more complicated. Engaging in a detailed discussion of militant jihad — a complex subject informed by centuries of scholarship — risks drawing the scrutiny of law enforcement and, Qadhi fears, possible prosecution. If he were to acknowledge that Islamic law endorses the legitimacy of armed resistance against Western forces in Muslim territory, he could give a green light to the very students he claims he is trying to keep off the militant path. Yet by remaining silent, Qadhi says he is losing the credibility he needs to persuade them of his ultimate message: those fights are not theirs, as Westerners, to fight. “My hands are tied, and my tongue is silent,” he said.

Militant clerics abroad have filled the void, none more than Anwar al-Awlaki, the American preacher who is now believed to be in hiding in Yemen with Al Qaeda in the Arabian Peninsula. Awlaki has been linked to numerous plots against the United States, including the botched underwear bombing. He has taken to the Internet with stirring battle cries directed at young American Muslims. “Many of your scholars,” Awlaki warned last year, are “standing between you and your duty of jihad.”

It was near midnight last October when Qadhi’s teenage acolytes surrounded him at Thomas Sweet, an ice cream parlor in New Brunswick, N.J. Puma sneakers peeked out from under long robes. Suddenly the lyrics “shake your booty” blasted over the speakers. The young men leaned in closer, unfazed. Between helpings of mango-flavored sorbet, Qadhi pontificated on medieval Islamic theology. “We have a reasonable religion,” he said. “We’re a very logical, rational group of people.”

Qadhi’s students hang on his every word. They huddle around him — between classes, during meals, even in bathrooms — pinging him with questions. Their reliance on Qadhi is a product of contemporary Islam, a decentralized religion with no clear authority. Clerics with the highest level of scholarship are considered invaluable guides, especially in the secular West.

Qadhi was in New Jersey that weekend to teach a seminar on the concept of faith-led action. During a break, a dozen young men flocked to him once again. A soft-spoken engineer lobbed the first question: Wasn’t it hypocritical for the same Western imams who supported the Afghan resistance against the Soviets to now condemn the jihad against American troops? After all, another student asked, don’t civilians in Iraq and Afghanistan “have an obligation to do something to defend themselves?”