In London to promote her new film, Nine, Kidman froze out the BBC's main political presenter, Andrew Marr, when he asked her about the topic in an interview broadcast on Sunday.
Marr's question on Scientology, and Kidman's reaction were cut from the TV version of The Andrew Marr Show, but appeared in an extended interview on the programme's website.
Marr said: "Scientology. It is, a lot of people would say, a bullying cult."
Kidman replied: "I'm here to publicise Nine. If I was here to do an expose on myself then I'd be like, 'let's go,' but I have no interest in discussing any of that."
Marr said: "You don't want to talk about Scientology in any way at all?"
Kidman answered: "Nope. I'll talk about Nine."
Marr - who sparked controversy earlier this year by asking UK Prime Minister Gordon Brown whether he took pills to help him get through - backed down, launching into a question about Kidman's Academy Award-winning portrayal of Virginia Woolf in The Hours.
Kidman, who married country singer Keith Urban in a Catholic ceremony in Sydney in 2006, stars alongside Cruise's ex-girlfriend Penelope Cruz in the musical, Nine.
Earlier in the interview, Kidman said she and Cruise were "deeply committed" in their marriage at the time of filming the Stanley Kubrick film, Eyes Wide Shut, in London in 1999, two years before the couple divorced.
In a September interview, Marr told Brown he wanted to ask about "something everybody has been talking about in the Westminster village".
Marr said: "A lot of people in this country use prescription painkillers and pills to help them get through. Are you one of them?"
A shocked Brown replied: "No. I think this is the sort of questioning which is all too often entering the lexicon of British politics."
When Marr tried to press Brown on the issue, the prime minister said: "I've already answered that question."
