One recent Saturday night, about 50 Muslim scholars filed into a classroom at George Mason University's Arlington campus to hear the keynote address of their three-day conference on Islam and modernity. They had to watch it on a DVD.

The speaker, Geneva-based Muslim intellectual Tariq Ramadan, could not attend in person because his U.S. visa had been revoked. Yet to those in the audience, his moderate words sounded like the kind of message U.S. officials would applaud. He urged a serious dialogue on the "universal values" shared by Islam and the West and added, "We should not blame the West for our problems."

"I was sad more than anything else," Shahed Amanullah, a Georgetown University graduate student attending the conference, said of the decision to bar Ramadan from entering the country.

"There's a level of perfection expected of Muslims that is almost impossible to meet," he added. "People don't pay attention to the content of what we say. They look for a reason to mistrust us."

Starting today, Muslims begin observing Islam's holy month of Ramadan, a period of daytime fasting and prayer aimed at acquiring spiritual discipline and deeper faith. But as the George Mason incident underscores, many American Muslims feel more beleaguered and discouraged than at any time since the September 2001 terrorist attacks.

In the weeks after 9/11, American Muslims encountered an angry backlash that included violence. But many of them considered this to be an understandable and temporary emotional reaction, and the outbursts were tempered by many acts of kindness toward Muslims by non-Muslim neighbors and co-workers.

Three years later, many Muslims say the atmosphere seems much bleaker. Anti-Muslim sentiment appears to be hardening into a permanent feature of public discourse, and Muslim advocacy groups report an increase in hate crimes and discrimination.

Leaders of those groups acknowledge that continuing acts of violence by Islamic terrorists, especially beheadings in Iraq, have contributed to Islam's deteriorating image in this country. But, they add, so has a constant stream of invective against Islam by ill-informed talk radio and television pundits and some religious leaders.

A recent national poll found that almost one-third of Americans respond with a negative image when they hear the word "Muslim." Ibrahim Hooper, spokesman for the Washington-based Council on American-Islamic Relations, which commissioned the poll, said he has a folder of more than 800 e-mails against Islam or Muslims that have been sent to his organization in the last two years. The "viciousness" of such messages has gone way up compared with the period immediately after 9/11, Hooper said.

Many American Muslims believe that the U.S. government has contributed to the deepening of anti-Muslim sentiment by treating them more as foes than allies in the war against terrorism. They say the government has done this by singling out Muslims for special scrutiny at airports, investigating Islamic charities and detaining Muslims who eventually are found innocent of criminal activity -- all of which leads to a growing perception that the war on terrorism has become a war against Islam.

"I hear a lot of people saying that today, especially moderate Muslims, people I never thought would have this feeling," said Mohamed Magid, imam of the All Dulles Area Muslim Society, a mosque in Sterling.

Echoing other Muslims, Magid said he fears that there is "some element in the [Bush] administration intent on dismantling Muslim organizations and bringing them down. . . . It's very disturbing."

Immigrants feel especially vulnerable. Palestinian Osama Abu Irshaid, 30, who lives in Annandale and edits a newspaper critical of U.S. Middle East policies, said he and his friends carefully avoid saying anything on the phone that the FBI might interpret as a coded message. When they get together, he said, "we're talking about [how] it might be our last party. It might be our last picnic."

One friend, who has since left the country, used to sleep in his clothes in case he was arrested. He didn't want to appear on television in his pajamas, Irshaid said.

"When you live expecting the worst every day, this is not a life," he added.

Amanullah, 36, who was born in the United States and lives in Fairfax, said he struggles with the idea that the government's war on terrorism has become a conflict with Islam.

"A lot of American Muslims don't want to believe that. If they truly believe that, they would be more scared than they are already," he said. "But . . . when a person like Tariq Ramadan is pushed out, they think, 'I wonder, could it be true?' "

Ramadan, 42, was given a work visa in April so he could become the Henry R. Luce professor of religion, conflict, and peace building at the University of Notre Dame's Joan B. Kroc Institute for International Peace Studies. In July, the visa was revoked under a section of the USA Patriot Act barring entry to foreigners using a "position of prominence . . . to endorse or espouse terrorist activity."

Ramadan, who has visited the United States dozens of times, denies ever endorsing terrorism and has reapplied for a visa. "We very much want him here, and we are holding the position open," said Notre Dame spokesman Matthew Storin.

Some Muslims say the U.S. government has missed an opportunity to fully engage Muslims as partners in the intellectual battle against terrorists. The extremists "have taken the narrowest interpretation" of the Koran to justify their actions, Irshaid said, adding that Muslims like himself "can demolish them ideologically. I can confront them. I can dismantle their ideas [because] I'm using the same references, the same history and the same terminology. The American government will not be able to do that."

The Los Angeles-based Muslims Public Affairs Council has expressed disappointment that no American Muslims were included in the drafting of the federal 9/11 Commission report, even in sections addressing the United States's relationship with the Muslim world.

Taking note of the report's recommendation that the United States develop coalitions with Muslim nations to fight terrorism, council officials said in a news release that "no American Muslim occupies a policy making position in key agencies that deal with the Muslim world."

Council Executive Director Salam Al-Marayati said he is also disappointed in the U.S. government's response to his organization's recently launched National Grassroots Campaign to Fight Terrorism. Among other things, the campaign's materials instruct mosques to get training from local law enforcement on detecting criminal activity.

The FBI praised the council's initiative in a news release but has declined Al-Marayati's request for a joint news conference with senior government officials to publicize the campaign.

Despite their difficulties, some Muslims say they find much in common with non-Muslims when they engage them in everyday life at schools, streets and places of worship.

"The test of living is on a local level," said Afeefa Syeed, principal of Al-Fatih Academy, an Islamic school in Herndon.

The headscarved Syeed said that when she ran for the county Board of Supervisors last year, "I went door to door in Loudoun County, which is considered a highly conservative area [and] I had so many incredible conversations with people about growth, transportation and schools. Almost never did I have conversations about my faith or what I wear on my head."

Syeed said the experience "told me that we as Muslims underestimate ourselves, we underestimate how much tolerance there is in the community at large. . . . It gave me more of a sense of belonging than before."

This sense of belonging has motivated other Muslims to take some responsibility for how other Americans view Islam.

After 9/11, graduate student Amanullah said he found the rhetoric of most Muslim leaders so "simplistic and naive" that he founded www.altmuslim.com as a forum to candidly discuss problems in the Muslim community.

"I'm just so sick and tired of hearing that 'Islam is peace.' It's a conversation killer; it's an intellectual thought-killer. It's meaningless," Amanullah said. "Most Americans want to know that Muslims are dealing with our own problems even if they're not solved. What they don't want to hear is that everything is fine with us . . . this kind of denial mode."

"We underestimate how much tolerance there is," says Afeefa Syeed, principal of Al-Fatih Academy in Herndon.What society expects of Muslims "is almost impossible to meet," says Web site founder Shahed Amanullah.Palestinian Osama Abu Irshaid is guarded in his phone conversations for fear the FBI may be listening.Afeefa Syeed, principal of Al-Fatih Academy, says for Muslims, "the test of living is on a local level."