Leah Remini Reveals Her Life as a Scientologist: 'You Lose Touch With the Real World'

Actress Leah Remini is speaking out about her defection from the Church of Scientology.

Read: 'Going Clear' Documentary Claims Church of Scientology is Blackmailing John Travolta

Remini spoke with 20/20's Dan Harris for an exclusive interview airing on Friday at 10 p.m. on ABC.

In the interview, she reveals that once she became critical of Scientologist Tom Cruise, it was time to go. 

"Being critical of Tom Cruise is being critical of Scientology itself… you are evil,” she said.

Remini has written a new tell all book Troublemaker: Surviving Hollywood and Scientology. She writes about growing up in the church and says it was tough severing ties after 30 years.

Read: Was Nicole Kidman Not Invited to Daughter's Scientology Wedding?

"As time goes on, you start to lose touch with the real world. The mindset becomes 'us against them,” the former King of Queens actress told 20/20. “The decision to leave is you are giving up everything you have ever known and everything you have worked for your whole life.”

Remini says the best thing she ever did was leave Scientology.

"I feel that people need to understand this has been my whole life. I want them to understand how it happens,” she said.

The Church of Scientology earlier issued the following statement to INSIDE EDITION: "It comes as no surprise that someone as self-absorbed as Leah Remini with an insatiable craving for attention would exploit her former faith as a publicity stunt by rewriting her history with it, including omitting that she was participating in a program to remain a Scientologist by her own choice, as she was on the verge of being expelled for her ethical lapses."

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