Video: Leah Remini Opens Up About Leaving Scientology, Blasts Tom Cruise

Actress Leah Remini, who famously left the Church of Scientology and will soon release a tell-all memoir, says that Tom Cruise's prominence in the organization is one of the reasons why she left.

"Being critical of Tom Cruise is being critical of Scientology itself," Remini told ABC's 20/20 in a clip, as seen in the clip above. "You are evil" in the eyes of the Church if you were to speak out and criticize Scientology's most famous member.

The interview, which will air Friday night, will touch on Remini's personal history with Scientology and her decision to leave. "I feel that people need to understand this has been my whole life," she says.

Remini joined the religion when she was only 9 years old, but left in 2013, filing a missing person's report on the wife of Church leader David Miscavige on her way out the door.

Firing back as they always do, the Church responded to the announcement of Remini's book, titled Troublemaker: Surviving Hollywood And Scientology, as a "pathetic quest to get publicity and seem relevant."

"As time goes on, you start to lose touch with the real world," Remini said. "The decision to leave is you are giving up everything you have ever known and everything you have worked for your whole life."

Remini's interview will air on ABC on Oct. 30 at 10 p.m.