Here's Why HBO's New Scientology Documentary Is So Critical Of Tom Cruise

"Going Clear," HBO's explosive new documentary on Scientology, just premiered on Sunday at the Sundance Film Festival, but it's already causing a lot of controversy.

The film, directed by Alex Gibney based on Lawrence Wright's best selling book of the same name, alleges that the religion enforces physical and psychological abuse, among other bombshell reports.

According to Variety's Brent Lang, who saw the film at Sundance, the documentary also "points the finger of blame squarely at two of Scientology's most famous practitioners, John Travolta and Tom Cruise, and shames them for turning a blind eye to the alleged mistreatments."

Lang spoke to filmmaker Alex Gibney, who also did the 2005 Enron documentary "The Smartest Guys in the Room," and "Going Clear" author and Pulitzer Prize winning journalist Lawrence Wright, about why Scientology relies so heavily on its celebrity members, like Tom Cruise.

"He's vital to the church, because he is the most famous Scientologist," Gibney told Variety of Cruise. "He is their key guy and he is a magnet for people. Very often you'll ask people what's Scientology and they'll say, 'isn't that the religion with Tom Cruise'? So he's their poster boy."

But both Gibney and Wright accuse Cruise of turning a blind eye to mistreatment in the church.

Wright tells Variety that the actor "has spent countless hours out on the Sea Org base," where especially harsh punishments are inflicted like "sleeping on the floor on bedrolls with ants crawling around, [people] abused physically, and made to lick the floor or the toilet with their tongue."

"It's just unbelievable degradation," Wright continues. "If he's [Cruise] ignorant of that then it's willful on his part."

Adds Gibney: "The other thing about Cruise is that he's been the beneficiary of this unbelievably low-paid Sea Org labor. These people are being paid forty cents an hour and they're tricking out Cruise's cars."

Wright bluntly states: "We hold people like Tom Cruise and John Travolta and others responsible for not demanding change inside that church."

"By not speaking out," argues Gibney, "it's a kind of an endorsement and I think that's why we're [the documentary] right and properly critical."

But Scientology's involvement with celebrities goes beyond just Tom Cruise and John Travolta. The church's headquarters is based in Hollywood, and actively recruits people in the entertainment industry.

Wright explains to Variety:

This goes back to the founding; when L. Ron Hubbard created the Church of Scientology, he decided to make its headquarters in Hollywood, because he had a very perceptive notion that there is something that all Americans do worship and it's celebrity and the capital of celebrity is Hollywood. He set out very early to make it a Scientology town.

They always wanted celebrities who could sell Scientology just like the people on the front of the Wheaties box.

Read Wright and Gibney's full interview with Variety here.

"Going Clear," which has 160 lawyers preparing for the litigious Church of Scientology's response, premieres March 16 on HBO.

Earlier this month, the church published a full-page ad in The New York Times accusing the film of reporting false claims about the controversial religion.

The Scientology ad calls out "Going Clear" director Alex Gibney for supposedly not allowing the organization to respond to claims made in the film.

Specifically, the ad asks whether the documentary is "a Rolling Stone/UVA Redux" - a reference to a now notorious article in the magazine about rape at the University of Virginia.

Former Scientology members hope this film will have the power to force major shifts within the church.

"I hope this movie increases public pressure for the church to change its abusive practices," one former Scientology member told The Times.