No, that was not the premise of Cruise’s latest screen fantasy, Steven Spielberg’s remake of War of the Worlds, but that of another science-fiction legend that our hero has lately been doggedly promoting.

In L. Ron Hubbard’s box-office wonder, we mortals can challenge the will of Xenu, the nefarious warlord, only by purifying our spirits through a secretly priced series of study courses. Cruise, a Scientology veteran, has now reportedly progressed so far as an “Operating Thetan” in the Church that he has chosen generously to proselytise for the cause in a series of film-pegged interviews. This one-man marketing blitz must make him the (non-alcoholic) toast of Hollywood’s Scientology Celebrity Centre: first-time inquiries are up sharply on last year, sales of Dianetics books have tripled, and “Scientology” has become one of the fastest-growing web searches.

Cruise is clearly speaking from a deep personal belief. The scandal is that our supine, celebrity-hungry media have cravenly let him publicise this controversial organisation on his own uncritical terms.

Thanks to his recent pronouncements, we now know that Scientology has “the only successful drug rehabilitation program in the world”, that psychiatry (as his Church teaches) is a Nazi “pseudoscience” and that antidepressants are worthless — tsk, Brooke Shields — as there is “no such thing as a chemical imbalance”. We have learnt that Cruise had a Scientology “massage ” tent brought on to Spielberg’s set (“to help the sick and injured”), that he is a Scientology “helper” who can save criminals and drug-addicts through the Church’s Narcocon programme and that his new fiancée, Katie Holmes, joyously “digs” Scientology too.

All very enlightening to the fix-grinned trivia merchants granted audiences with the great star — but in their fear of earning disapproval, too many so-called journalists have simply indulged Cruise’s questionable assertions. As talented an actor as he is, his active promotion of Scientology interests at a time when the group is pushing its medically questionable programmes in American schools and lobbying to legislate against psychiatry, demands closer scrutiny in the public interest. Instead, the tough questions go unasked and unanswered, with even Readers Digest — which once investigated what it concluded was “a frightening cult” — now reduced to attending a Scientology “immersion course” in order to interview Cruise for a cover story.

So here are a few questions that the media ought to have asked Cruise. Tom, if you are so keen to place the Church firmly at the heart of public debate, why is it so anxious to suppress open discussion about its treatment record or finances? Why have defecting members been held to “billion-year” contracts to stay silent? And why have journalists investigating the church so often alleged that they met campaigns of personal intimidation and harassment? Richard Behar, who wrote an award-winning cover story for Time magazine in 1991, headlined “The Thriving Cult of Greed and Power”, claimed that in researching his piece, “at least ten attorneys and six private detectives were unleashed by Scientology and its followers in an effort to threaten, harass and discredit me”. The Church also brought a $415 million libel suit over Behar’s article — ultimately thrown out ten years later, but not before it served to warn off other potential investigations.

The chill evidently lingers still. “Don’t ever defend; always attack,” advised Hubbard, whose strategies continue to shape the group’s expansion 19 years after his death. “The purpose of the lawsuit is to harass and discourage rather than win.” Enemies of the Church, he suggested, “may be tricked, sued or lied to or destroyed” — hardly sentiments normally embraced by a mainstream religion.

It may be naive, but I had always considered it a noble duty of the press to stand up on behalf of the powerless — people like Lawrence Wollersheim, who spent $150,000 on Church treatments but claimed that his mental health deteriorated until he was suicidal. After a 22-year court battle, the Church finally paid $8.6 million to settle. Maybe Tom has forgotten this case; the next time he proselytises on behalf of Scientology, perhaps an interviewer should remind him.

Still, don’t hold your breath. As Hubbard quickly realised, a celebrity’s endorsement can deflect attention from all those difficult questions and legitimise a secretive, all-controlling organisation. Fifty years ago he urged supporters to target “quarry” such as Greta Garbo and Walt Disney. Today, as the Church aggressively works to gain mainstream acceptance, it has built its credibility on spokespeople such as John Travolta, Kirstie Alley and the musician Beck.

Shame on the media for playing the gurus’ game. If Tom Cruise continues to use his public standing to promote the organisation shaping his private beliefs, then he needs reminding why so many former members have articulated serious misgivings about the Church of Scientology. A boycott of his film, true, is unlikely to silence him. In the meantime, it is the least the sceptics can do to show their disdain.

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