Oct. 24, 2009  -- Celebrities and the Church of Scientology seem to go hand-in-hand. And actor Tom Cruise is arguably the world's best-known celebrity Scientologist.

"She goes, 'I don't really understand who you are,'" Cruise says in a video made for a Scientology event that was leaked onto the Internet last year. "And I said, 'OK, I'm a Scientologist.'

"There's nothing part of the way for me," Cruise says on the video, laughing. "It's just [makes voom sound]."

Tom Cruise first burst onto the scene in a pair of white socks, and not much else, in "Risky Business." Then he was fighter pilot, a bartender, and by the time he appeared in "Jerry Maguire," he'd become the most successful movie star on the planet -- and deeply involved in Scientology.

Amy Scobee was a member of Scientology for 27 years. She was a Church executive who helped expand Scientology's outreach to celebrities. She spoke with "Nightline."

Nightline: ...Presbyterian Church doesn't have a wing that emphasizes reaching celebrities ...Why do you think there was this emphasis on celebrity?

Scobee: ...One of the purposes of Celebrity Centre is to make celebrities walking success stories of Scientology.

Tommy Davis is the director of public affairs for the Church of Scientology. His mother is the actress Anne Archer, who was nominated for an Academy Award for her role as a betrayed housewife in the movie "Fatal Attraction."

Nightline: ...Why was there this exceptional approach to celebrities?

Davis: Well...

Nightline: What's the purpose of that?

Davis: What you have in Scientology is you have a lot of artists who are Scientologists. Some of them are well known. ...the Celebrity Centre, which is that arts and culture branch of the Church first began, it was actually started and founded by and gotten going by Scientologists who are artists.

Scientology was founded by science fiction author L. Ron Hubbard in the early 1950s. One of the key practices is "auditing," which is a kind of counseling session in which a person's unconscious thoughts from painful experiences are purged, often with the help of a trained auditor and a device known as an "e-meter."

Bruce Hines left the Church in 2003 after 24 years.

Hines: This e-meter, this electrometer, which works on the same principle as a lie detector, even though they say, "No, this isn't a lie detector." But it's the exact same principle.

Nightline: But it indicates some kind of electrical pulse?

Hines: It sends a current through your body. ... And the theory is is that when you have emotional charge ... it changes the resistance of the body. So that changes the current. And that ... and it makes this needle move.

"Nightline" spoke with Tommy Davis.

Nightline: Has the e-meter ever been subjected to randomized clinical trials to assess its efficacy?

Davis: I have no idea. I don't know why it would be. It works in Scientology and that's what people use it. I don't know why it would be subjected to random clinical trials.

Nightline: Because it's a...a mechanism for therapeutic care you just said...

Davis: In a religion.

Nightline: But has it ever been tested objectively is what I'm asking?

Davis: I mean it gets used every day by Scientology counselors.

Nightline: I'm not asking that. I'm asking...

Davis: To my knowledge, no. ...And as far as evidence of the e-meter and its efficacy, the evidence of that is in those Scientologists who have used it to great benefit. And as far as the Church of Scientology is concerned, it's the only evidence that matters, is the people and the results.

From the start, L. Ron Hubbard set out to attract celebrities, believing high profile public figures would be its most effective evangelists.

Nightline: Can you recall any celebrities who came into the Centre when you were there?

Scobee: I met John Travolta, Kelly Preston, Priscilla Presley, Lisa Marie, Edgar Winter, Isaac Hayes, uh, Tom Cruise.

After Hubbard died in 1986, David Miscavige became the Church's leader -- and soon embraced Tom Cruise with great fervor.

Tom Cruise: Church's Most Celebrated New Member

Nightline: But I guess it ... it's helpful, isn't it, if ... uh, you're an organization with an individual as well known, as ...famous, as successful as Tom Cruise.

Davis: Sure.

Nightline: He's a...

Davis: Of course.

Nightline: He's a good advocate?

Davis: Oh, look ... I think anybody who would complain about having successful, well known, happy ... uh, people ...

Nightline: John Travolta, Kristie Ally.

Davis: ...of...of... their group, I'd think you'd be crazy to (laughs) complain about that.

Bruce Hines says he helped prepare for the arrival of the Church's most celebrated new member, who had decided to fully commit to Scientology by staying at the International Base in California for a few months of services.

"I was part of the preparations where David Miscavige brought Tom Cruise to the International Headquarters," Hines said.

And Hines says nothing was to be spared. "...And he had the very best auditors and the very best people looking after him," said Hines. "...Just the ... the best treatment that anyone could possibly get, so that he got a favorable impression of Scientology."

Church's Treatment of Celebrities

Marty Rathbun left the Church in 2004 after 27 years. He was a top lieutenant to David Miscavige.

Nightline: Did you audit Tom Cruise?

Rathbun: Yeah, extensively...

Nightline: They were given what, a celebrity environment?

Rathbun: A cel--

Nightline: Pampering?

Rathbun: You got it. You got it.

Nightline: And who was doing that?

Rathbun: Miscavige, man. I mean, that was his thing. It's all about image. ...He's flying across the country in Tom Cruise's jet. ...It's all about living the high life and being a powerful guy who is looked up to by the rich and famous.

Tommy Davis said the Church does not indulge or pamper celebrities.

In recent years, Tom Cruise has been more confident about publicly asserting Scientology principles -- particularly its rejection of psychiatric medicine.

"Here's the problem," Cruise told host Matt Lauer in a "Today" show appearance. "You don't know the history of psychiatry. I do.

"Matt. Matt, Matt, you don't even-- you're glib. You don't even know what Ritalin is."

Rathbun says the Tom Cruise he now sees on TV is not the Tom Cruise he once knew.

Rathbun: I watch him on Matt Lauer. And I go, "That ain't Tom Cruise. That's David Miscavige. That's not the Tom Cruise I knew two years ago."

Nightline: You're referring to the moment when he attacked Brooke Shields for suffering post-natal depression and--

Rathbun: Attacked Matt Lauer, I mean, he's talking--

Nightline: For not understanding--

Rathbun: --he is talking to Matt Lauer like David Miscavige talks to his staff. "You're glib, man, you don't get it. You don't understa--" you know.

When asked by "Nightline" if he supported Cruise's comments on the Today Show, Tommy Davis said: "I support anybody who is going to be out there talking about the dangerous effects of drugs..."

Nightline: But with the greatest respect, Mr. Davis, Tom Cruise is an actor. He's not a medical academic. He's not a clinician. ...Do you really think he's qualified to denounce an entire field of medicine?

Davis: Well, I think your comments right there are actually quite degrading of actors and artists...

Nightline: ...What right do they have?

Davis: They have every right...

Cruise was one of many celebrities to join the Church. In 1998, actors John Travolta and Kirstie Alley told ABC News how much Scientology has helped them.

"The basic thing that I think Scientology helps people with is to rehabilitate their own spirit, their own nature, their own personality that was sort of buried or lost somewhere along the way," said Alley.

"It's given me all aspects of life back to me where I can move through life confidently, I can move through life feeling fulfilled, I look forward to life every day," said Travolta.

Recently, speculation has swirled about Travolta, who famously produced and starred in the film, "Battlefield Earth," based on a book by L. Ron Hubbard.

"Nightline" spoke with Marty Rathbun, who says he audited Travolta.

Nightline: What sort of a man was he?

Rathbun: He's a wonderful man. He's a great guy. He's very love -- one of the more loving persons you ever want to meet, sensitive, caring.

It was at the family's island retreat that Travolta's 16-year-old son, Jett, who had autism, died from a seizure, in January.

"Nightline" asked Davis if the Church had ever advised Travolta not to allow his son take certain medications.

"Absolutely not. It never happened. The Church never advised them on ... in ... in any way, shape or form, whatsoever, on any aspect of, uh ... of their son's treatment. Never have. And never will," Davis said.

Nightline: As you know, Mr. Travolta and his wife suffered a very great tragedy recently. ... Do you know if the Church ever advised them not to allow their son to receive certain medications for conditions?

Davis: Absolutely not. It never happened. The Church never advised them on ... in ... in any way, shape or form, whatsoever, on any aspect of, uh ... of their son's treatment. Never have. And never will.

The tragic death has lead to tabloid speculation that John Travolta might leave the Church of Scientology, something the Church and Travolta's publicist fiercely denied -- and last week, Travolta, his wife, Kelly Preston, and Tom Cruise were at major Scientology celebration in England.

Secrets of Scientology

The Church says there is no aspect of life that cannot be improved through the application of Scientology principles, some of which are treatments conceived by L. Ron Hubbard. One such procedure, popular with celebrities, is called the "purification rundown."

"It's a sauna and vitamin program, some exercise to get your heartrate going and ... you would take high doses of ... dosages of Niacin," said Amy Scobee.

Scientologists believe it can dislodge toxins and poisons from the body.

Tom Cruise is a strong advocate of this treatment -- co-founding the New York Rescue Workers Detoxification Project, which uses L. Ron Hubbard's "purification rundown" principals for those exposed to toxic chemicals after the terrorist attacks of 9/11.

"When I started this project, it was because I was in a position where I knew that I could help," Cruise said at a project event.

Scobee had the treatment.

"When I did it the first time... it was one week..., and I felt, brighter and more alert," she said. "My skin was, you know, vibrant and stuff like that."

But far away from the limelight of celebrities, Scobee says the program can also be used to discipline Church staff members. She says she was once told to take part in a purification rundown that ended up lasting eight months.

Scobee: I was at 5,000 milligrams of Niacin for months and months. I don't know what that did to my body! (Laughs). I have no idea.

Nightline: How did you feel?

Scobee: I felt really, there was like gray stuff coming out of my skin, and I didn't know if it was like my insides coming out (laughs) or whatever that long of being in the sauna five hours a day every day.

Nightline: Five hours?

Scobee: Yeah.

Nightline: And you kept going?

Scobee: Yeah.

Nightline: What happened when you did it for eight months?

Scobee: That was when I, uh, decided I didn't want to be there anymore ... to satisfy somebody else's demands on ... on me, to fix me, because of their preconceived ways.

The Church denies Scobee's characterization and says the program is a "religious service," and to claim it as a "kind of perverse punishment" is "gross in the extreme."

Perhaps the most sensitive aspect of the Church's theology concerns confidential scriptures meant only for higher level Scientologists.

According to former Church insiders, these documents describe L. Ron Hubbard's belief in an intergalactic emperor called Xenu who brought the spirits of his people to earth 75 million years ago, burying them in volcanoes. These spirits, the story goes, have stuck to the bodies of people living today in the form of "body thetans."

"They have had some really bad experience millions, billions, trillions, actually quadrillions of years ago, which is way older than the Big Bang basically...," said Bruce Hines. "You're supposed to, isolate ... and communicate with them telepathetically, so that they go away."

Tommy Davis spoke with "Nightline."

Nightline: Do you believe that ... a galactic emperor called Xenu ... brought his people to earth 75 million years ago and buried them in volcanoes?

Davis: OK.

Nightline: Do you believe that?

Davis: Martin, I am not going to discuss the disgusting perversion of Scientology beliefs that can be found out commonly on the Internet and be put in the position of talking about things for ... that ... talking about things that are so fundamentally offensive to Scientologists to discuss...

Nightline: Well, I ... I have the burden of my own journalistic responsibility ...

Davis: Uh-huh.

Nightline: ... that I bring to this meeting and I hope that, I've been appropriately respectful of you in my asking of the questions ...

Davis: Well, you haven't to the degree that the question that you asked me you know, by virtue of the fact that it's been made very clear in other media entities that it's something that we consider offensive ... It is in violation of my religious beliefs to talk about them.

Nightline: So, just for clarification ... just for clarification, do you personally believe ...

Davis: I'm going to stop you, if you're going to ask me that question again and you're going to repeat things about volcanoes and this kind of thing and so on and so forth, I will stand up and walk out, Martin. Because ... because what you're doing by doing that is you are intentionally asking me things which you know I find offensive, and you're insisting on asking me. So I'm asking you one more time...

Nightline: Mr. Davis ...So, for a moment, if you wouldn't mind, I'm not trying to offend anybody. I'm just trying to ask you a series of questions about the public face that you have. I'm not trying to mock you, I'm trying to understand what your beliefs are.

Davis: Sure.

Nightline: You've explained what auditing is....you've explained the growth of the Church, you've done all of those things.

Davis: Uh-huh. Uh-huh. Sure.

Nightline: I am asking you in the context of those questions, in the context of those questions, is it true that L. Ron Hubbard said that understanding the origins of the human race and described through Xenu --

At this point Davis stood up and left the room.

'We're Counting on You'

Tom Cruise is a close friend of the ecclesiastical leader of the Church of Scientology, David Miscavige.

Cruise recently received the organization's "Freedom Medal of Valor" at a prestigious ceremony.

"I want to tell you something. I have never met a more competent, a more intelligent a more tolerant, a more compassionate being," Cruise says in a video of the ceremony. "....To LRH! [salutes photo of L. Ron Hubbard]."

In a report on Oct. 22, 2009, "Nightline" focused on allegations made by former high ranking Scientologists who claim leader David Miscavige repeatedly struck subordinates.

"He just walked up and he hit me on the side of the head. It was a ... he didn't have a closed fist. But it was an open hand," Hines said. "But it was ... it definitely hurt and it definitely knocked me back."

"I saw him ... attack [Mike Rinder] while he was sitting in a chair and hitting him upside the head," said former Church executive Marty Rathbun. "And then -- in -- and then wrestling him around the neck and ... throwing him to the ground... I saw at least a dozen times, this happen."

The church denies David Miscavige ever hit anyone. Sworn affidavits given to ABC News from over a dozen current Scientologists describe the allegations of abuse as "vile falsehoods" and say it was actually Marty Rathbun who was abusive.

Rathbun concedes he was violent, but says he was encouraged to be physical by Miscavige. He and the other accusers believe Tom Cruise is too supportive of the Church's leader.

"Tom Cruise, I don't appreciate the fact that he's supporting David Miscavige," said Scobee, "because either he's supporting him and ... and dumb to the fact that he is a total tyrant, or he's in agreement with it ... and either way that is really not OK."

And Rathbun hopes that the other most famous Scientologist, John Travolta, will re-consider his relationship with Scientology in light of the allegations of violence.

Nightline: What do you think of his position at the moment? Do you think that he's likely to leave?

Rathbun: I think if [Travolta] were exposed to the truth, the truths that are being spoken...about what really is going on behind the façade, I don't think he would continue to support that organization. ...I think he'd check out in a heartbeat.

In a letter sent to Nightline yon October 22, Tom Cruise's attorney called the actor "a man of spirit, intelligence, and independence." He said, "Mr. Cruise is aware of the claims made against Mr. Miscavige by former members of the Church of Scientology. He does not believe them."