Kirstie Alley of "Cheers" fame says it saved her life.
John Travolta says his career took off -- including landing the Vinnie Barbarino gig on "Welcome Back, Kotter" -- after he took up Scientology in 1975.
Tom Cruise credits the religion with helping him overcome dyslexia. And now, in an increasingly public way, he is spreading the word, including to his new squeeze, "Batman Begins" actress Katie Holmes.
She has said she's "really excited" about learning more.
Scientology officials in Chicago say they've seen an uptick in interest -- including from the media -- in the last few weeks as the Hollywood couple known as TomKat goes on about the religion.
Scholars who study Scientology also say they've been flooded with calls from reporters in recent days.
"I never thought Tom Cruise's love interest would impact my life," cracked Stephen A. Kent, a University of Alberta, Canada, professor who has written about Scientology.
The latest spotlight to shine on the controversial religion can be traced to Cruise. In recent months, he has set up a Scientology tent on a movie set, taken movie execs on Scientology tours, said Brooke Shields is misguided for using the antidepressant Paxil for postpartum depression and had a heated exchange with the "Today" show's Matt Lauer over Scientology and psychiatry in an interview that aired Friday.
"Scientology is something you don't understand," Cruise told Lauer.
Whether the latest publicity will translate into more church members remains to be seen. Negative publicity, readily available on the Internet, could have an adverse effect as well, although some scholars say the fiercest criticism has dropped off over the years.
The Los Angeles-based church has battled its critics for years with a series of expensive lawsuits, fighting to clear its name and keep its secret writings off the Internet.
It also fought with the Internal Revenue Service for years to receive tax-exempt status. It won that battle, and its officials reject suggestions that it's more of a money-making venture than religion.
"It remains one of the more controversial new religious movements, but I think all of the more controversial groups have decreased the tension with larger society over the last decade or two," said David G. Bromley, a Virginia Commonwealth University professor who has studied Scientology.
"There are still a number of countries where it's not accepted as a religion, but it has been in the United States. I think the level of tension is certainly declining."
The church says its worldwide following is more than 8 million, including about 20,000 in the Chicago area. The actual number of practicing members is lower, however, because church estimates include people who have had an initial interest but backed away.
Other high-profile people identified with Scientology include Elvis Presley's daughter, Lisa Marie; musicians Isaac Hayes and Chick Corea, and actresses Jenna Elfman and Kelly Preston, Travolta's wife.
The church is eager to spread positive testimonials, and many experts don't dispute the helpfulness of Scientology.
"That's why so many people become Scientologists," said J. Gordon Melton, director of the Institute for the Study of American Religion and the author of a book on Scientology. "If it wasn't helpful to them, the church would dry up and go away."
Still, critics question such things as the high cost to advance deeply into the religion's multitiered programs and the religion's Rehabilitation Project Force program for problem upper-level members.
Scientology, referred to by the church as an applied religious philosophy, was launched four years after the 1950 publication of L. Ron Hubbard's hugely successful book Dianetics: The Modern Science of Mental Health.
Hubbard, whose first initial stands for "Lafayette," was a prolific writer who penned everything from romance to science fiction. Before his death in 1986, he wrote more than 275 books and pamphlets.
Born in Nebraska in 1911, he began his studies of the mind and spirit in 1923. In 1938, he wrote a manuscript titled "Excalibur," which, according to his church, was the first writing to contain a reference to "Scientology" that appeared to describe its meaning -- "the study of knowing how to know."
After Dianetics came out, groups began to form to use the techniques in the book. In 1954, the first Church of Scientology was formed in Los Angeles.
Some of the fundamental beliefs of Scientologists are laid out in its publications: Man is an immortal spiritual being. His experience extends well beyond a single lifetime. His capabilities are unlimited, even if not presently realized. The aims of Scientology, according to the church, are a world without insanity, without criminals, without war.
It is a religion fiercely opposed to many other mental health practices, including psychiatry. On its Web site, the church refers to "other methods of alleged mental science" and says other practices "treat man as a 'thing' to be conditioned, not as a spiritual being who can improve enormously."
Scientologists strictly oppose mind-altering drugs, including psychiatric drugs -- such as Paxil.
Scientology believes people are basically good and, with Dianetics, offers tools to improve. But it goes beyond just self-help. It is a religion complete with churches, Sunday services and a detailed theology.
"The idea is that at some point in the prehistoric past, the soul, which is the real us, the essence of what we are, falls into the body, falls into material existence," said Melton. "After a period of time, it moves from body to body, and it forgets who it is. So the object of the religion is to allow the soul to remember its true nature and then begin to function as a free soul."
Scientologists use several methods to get people started, including a device called an E-meter, said to measure stress and root out problems. There are also one-on-one sessions called "auditing."
"Auditing is basically a procedure Mr. Hubbard started to help a person locate problems and stress or pain and discomfort, to relieve themselves of unwanted emotions or sensations," explained Mary Anne Ahmad, director of public affairs for the Church of Scientology of Illinois.
A goal of the auditing sessions is to ultimately be "clear" of what is referred to as the "reactive mind," the part of the mind that is not under a person's control, that works on stimulus-response.
According to church teachings, during times of emotional or physical pain, the reactive mind takes over and records images -- called engrams -- which can later lead to problems that a person can't explain. To become a "Clear" is to erase the engrams and no longer be under control of the reactive mind or its ill effects.
But it's not cheap. Auditing can cost thousands of dollars when done by a professional auditor. Ahmad said costs can be reduced when local church auditors trade services. But members also pay for a series of courses and for literature. Some experts estimate the cost can reach into the hundreds of thousands of dollars.
Scientologists believe in a god or a supreme being, said Ahmad.
"We are all denominational," she said. "A person can go to the Catholic Church or the Jewish synagogue or an Islamic mosque or Hindu temple and still come and be a Scientologist. We have all those and more. So a person's own idea of what God is, that's his own idea.
"One of the basic principles of Scientology is what's true for you is what you have experienced to be true."
Scientology says it has more than 3,200 churches, missions and groups in 154 nations. In Chicago, it has a storefront at 3011 N. Lincoln. There are also missions downtown and in Evanston and Des Plaines.
Volunteer ministers from the church fan out to festivals all over the city and have rushed to disasters to help.
At the North Lincoln church, newcomers are shown an orientation film that aims to dispel myths about the church's beliefs and finances. The narrator says at the end that the viewer can leave and avoid Hubbard's teaching, but then adds: "It would be stupid, but you can do it."
For years, controversies dogged Scientology. In Germany, it's viewed not as a religion but as a money-making scheme. Scientologists have been banned from public service, even forced to remove their children from public schools.
The French National Assembly in 2000 unanimously passed a bill to make it easier to crack down on what the government considered cults, including Scientology. And in 2001, President Bush disparaged it by saying: "I have a problem with the teachings of Scientology being viewed on the same par as Judaism or Christianity."
The church rejects the cult label, and some experts in the United States agree. Said Virginia Commonwealth's Bromley: "Cult is a four-letter word for a religion you don't like."
Another controversy surrounds stories being circulated about the purported secret beliefs of Scientologists, including claims their theology traces back to a space-age story about an evil galactic warlord named Xenu sending souls to Earth 75 million years ago. Ahmad, the local Scientology official, said those claims are "bogus" and "taken out of context" by opponents and critics of Scientology. Those claims also offend Scientologists, she said.
"It's to make us look weird, and we're not," Ahmad said.
The biggest strike against the church, some say, is its newness.
"What is particularly true in America, when new things come along, if they are significantly different in any way, we as a culture test them out," Melton said. "Nobody is picketing Christian Science [anymore]. Nobody is calling them a cult."
Said Ahmad, "Look what happened to the Catholics in Roman times. They had their heads cut off. They were thrown to the lions, for heaven's sake. At least they're not doing that."
One part of Scientology that has led to government investigations, raids, court rulings and a lot of raised eyebrows is a gadget called the E-meter.
Short for electropsychometer, the tabletop E-meter is a key part of Scientology's one-on-one "auditing" sessions. A person getting help holds on to two metal electrodes and is asked questions by a specially trained auditor or told to think about certain experiences.
A tiny flow of electricity -- about 1.5 volts -- passes through the person with the aim of detecting resistance. A gauge on the machine shows results. There is no detectable sensation.
Scientologists say the device can measure the spiritual state or change of state of a person by detecting areas of spiritual and mental distress, travail or trauma. By watching jumps in the needle, an auditor helps the person locate areas of concern to be handled in auditing sessions.
Full gains in auditing, Scientologists say, are impossible without the E-meter, which can be adversely affected by cool rooms, calloused hands and tight shoes.
Scientology founder L. Ron Hubbard had the machine built to his specifications in 1959 and quickly faced allegations that the device was a useless form of quackery.
In 1963, the U.S. Food and Drug Administration seized vanloads of E-meters during a raid and sought to ban their use. The Church of Scientology, which claims it has been persecuted by the government for years, fought the FDA, and in 1971, a judge said the machines should be returned.
But the judge also ruled that the devices could not be advertised as a treatment for disease. Current Scientology literature says the meter cannot diagnose or cure anything and refers to the machine as a religious artifact.