Systems of belief in America that fall outside the Christian-Judeo tradition are now referred to as "new religious movements" - a term scholars coined to avoid the sinister baggage often associated with the word "cult."
Many of these movements, however, are hardly new - and 99.9 percent of them do not pose danger, scholars say.
America's diverse religious landscape began with its first European settlers, the rebellious Puritans, and has evolved rapidly - particularly after the U.S. government loosened its immigration laws in 1965, which opened the door to a host of Asian and Southeast Asian religions.
Not surprisingly, this infusion of religious diversity created a host of misconceptions about the potential danger these belief systems can cause, scholars say.
The "anti-cultist" sentiment was compounded, and somewhat legitimatized, 25 years ago when Jim Jones and 900 members of the Peoples Temple committed suicide in Guyana.
"Jonestown came at a moment when anti-cult sentiment was extremely high," said Rebecca Moore, a religion professor at San Diego State University. "Jonestown validated all the warnings anti-cultists were making."
Scholars say it is tough to say when religion becomes dangerous. Moore said some of the characteristics, however, include:
Recent editions of J. Gordon Melton's Encyclopedia of American Religions lists 2,300 active religious groups in the United States, with most of them having at least 2,000 members.
The majority of these are considered mainstream groups; the ones characterized as new religious movements or those that fall outside the mainstream Christian-Judeo tradition, such as Scientologists and Spiritualists number well below 1,000, scholars estimate.
Many of these "new" movements have flourished, and are now considered mainstream by most people, said Timothy Miller, a University of Kansas professor who has traced the progression of many of these groups.
Miller said no other new group has had greater influence, or staying power, than the Church of Jesus Christ of Latter-day Saints, or Mormons, a religion founded in upstate New York on the basis of a series of revelations that founder Joseph Smith said he received in the 1820s.
The Mormons have been attacked since their inception - so much so that they were forced to move from New York to Ohio to Missouri to Illinois and finally, to Utah. There are about 80,000 Mormons now living in the Bay Area, said Jay Pimentel, spokesman for the LDS church. Despite the controversy that once surrounded the church, including its endorsement of polygamy until the early 20th century, Pimentel said things have changed.
The 2002 Olympics in Utah, he said, was a kind of litmus test for many Mormons to see how they would be received and treated.
"That confirmed to me that the church is treated and viewed much more in the mainstream than not," he said.