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Religious visas (search) allow foreign nationals in religious occupations to enter the United States and work for nonprofit religious organizations.

Generally, the majority of religious visas have gone to Christian ministers. For the past five years, however, scores of Muslim clerics from countries such as Saudi Arabia, Jordan and Pakistan have been let in on religious visas. Once here, many make provocative comments.

"The reality is that radical Islamic clerics, and even terrorists, have used religious visas to come to the United States," Islamic terrorism expert Steven Emerson (search) told FOX News. "It represents a clear and present danger to our security."

Upon arriving on a religious visa in California, Imam Wagdy Ghoneim preached support for suicide bombings. In Cleveland, Fawaz Damra praised the murder of Jews. In Tampa, Fla., Islamic studies professor Mazen Al Najjar raised money for terrorists.

Religious visas are easier to obtain than other work-related visas because applicants sponsored by institutions in the United States are afforded religious freedoms that protect them from intense scrutiny.

One risk, however, is that Islamic clerics often come from unconventional schools and mosques in remote areas where intelligence resources are lacking. That makes background checks and security assessments difficult.

"If 259 Pakistani imams are coming into this country," said Stephen Schwartz (search), executive director of the Center for Islamic Pluralism, "I would say that the probability is very high that the majority of them are financed by the Islamic extremist movement."

The Justice Department is struggling strike a balance between personal freedoms and national security, but it has taken little action thus far.

One proposed solution would be to create an Islamic institute staffed by U.S. religious scholars who are capable of examining clerics' credentials before obtaining their visas.

Click in the box near the top of the story to watch a report by FOX News' William La Jeunesse.