The newest study, released last month by the Graduate Center of the City University of New York, suggests there are no more than 2.8 million Muslims in this country. But the same study indicates that their numbers may have doubled in the past decade.
Some Muslims say the relatively low survey numbers reflect a pro-Jewish bias. The study involved a phone survey of more than 50,000 households and measured the population of all major American religious groups. The CUNY information is not the only evidence that Islam is among the fastest-growing religions in the United States.
Since 1995, the number of participants at mosques has increased by 10 percent, according to a study coordinated by Hartford Seminary's Hartford Institute for Religious Research.
That study, released in April, identified about 2 million Muslims who attended a mosque at least once during the previous year but asserted that there are an additional 4 million Muslims in the United States.
"Certainly in terms of the number of new congregations and growth rate of congregations, they're toward the top," said Dr. David Roozen, director of the institute, who was comparing Muslims with other religious groups with high growth rates.
But he doesn't know exactly how much Muslims are growing. And he doesn't place much weight on the fact that Muslims are more visible in America than ever.
"Remember the early days of the Moral Majority?" he said. "People said: `Where do all these evangelical Protestants come from? How many more are there?' Well, there weren't any more. They'd just found their public voice. That's what is happening in Islam."