Alex Gibney’s documentary, “Going Clear: Scientology and the Prison of Belief,” is ripe with shocking revelations about the secretive religious organization and the many celebrities at its center. But much of the film focuses on actor Tom Cruise, who has become Scientology’s most famous public face.

The documentary, based on Pulitzer Prize-winning author Lawrence Wright’s 2013 book by the same name, features interviews with former high-ranking Church officials, former members (including director Paul Haggis) and journalist Tony Ortega. Much of what they divulge contains extensive details about the numerous abuse allegations that have been brought against the Church. And while many people formerly associated with Scientology have spoken out against the alleged acts of psychological and physical violence, Gibney believes Cruise is the most vital voice yet to be heard.

“Cruise is the big kahuna and that’s why we’ve gone to the trouble of calling him out,” Gibney said at an HBO screening of “Going Clear” on Monday night. “We believe that he has a responsibility to say something about the abuse.”

The latter portion of Gibney’s documentary focuses on Cruise’s involvement with the Church, his relationship with current leader David Miscavige and previously unknown information regarding Cruise and the Church wiretapping Nicole Kidman’s phone before the couple’s divorce. While the film does not specifically connect Cruise to any of the abuse allegations, the director still believes that the actor “has an obligation to speak out.”

In January, both Gibney and Wright told Variety that they hold Cruise and John Travolta, another famous Scientology figurehead discussed in the film, responsible for “not demanding change” in the Church. On Monday, Gibney echoed that sentiment: “He can espouse his beliefs, that’s fine. But not to address the allegations of abuse seems to me palpably irresponsible.”

Representatives for Cruise were not immediately available for comment. But the Church of Scientology has issued statements against “Going Clear” since it premiered at the Sundance Film Festival earlier this year. In January, the organization ran an ad in The New York Times, purchased Google ads and published an article on the website of the Church’s magazine, Freedom, slamming the film:

The Church has documented evidence that those featured in Gibney’s film regurgitating their stale, discredited allegations are admitted perjurers, admitted liars and professional anti-Scientologists whose living depends on the filing of false claims. All have been gone so long from the Church they know nothing of it today. Yet Gibney and HBO stonewalled more than a dozen requests by the Church to offer relevant information about them, with more than 25 individuals with firsthand information eager to speak. To this day, neither HBO nor Gibney can deny that they have yet to present the Church with a single allegation from the film so the Church may have an opportunity to respond. The Church never sought special treatment, only fair treatment.

“Going Clear” is out in limited release and premieres Sunday, March 29, at 8:00 p.m. ET on HBO.