Actress Leah Remini blasts Scientology in exclusive ‘20/20’ interview

After 30 years as a Scientologist, actor Leah Remini turned her back on the church in anger. She’s written a book, in which she harshly criticizes her former faith, in part over incidents related to one of its most high-profile figures – Tom Cruise.

On Friday, she appeared in an exclusive interview on the ABC news magazine “20/20,” ahead of the release of her memoir, “Troublemaker: Surviving Hollywood and Scientology,” to voice her sentiments.

After serving in World War II, writer L. Ron Hubbard published a series of articles and then a book on what he described as a new approach to mental health. "Dianetics: The Modern Science of Mental Health" was first published in 1950, and it quickly became a best-seller. In 1954, Hubbard founded the Church of Scientology.

Hubbard and his children in December 1959. They are testing a device called an E-meter, which Scientologists say measures the body's electric flow as an auditor asks a series of questions that they say reveals sources of trauma. At the core of Scientology is a belief that each human has a reactive mind that responds to life's traumas, clouding the analytic mind and keeping us from experiencing reality.

Hubbard works in his greenhouse in December 1959.

Hubbard in the south of France in May 1968.

Hubbard talks with reporters in his office in 1974. Many groups and individuals have challenged Scientology's legitimacy as a religion. Scientologists have faced opposition from the medical community over the religion's claims about mental health, from the scientific community over its claims about its E-meters and from other religious groups about its status as a religion.

Hubbard poses for a portrait in New York in January 1982. He died in 1986.

The entrance to the Los Angeles headquarters of the church in March 1998.

Confetti rains down as actor Tom Cruise, left, embraces David Miscavige, the leader of the Church of Scientology, at the opening of a new church in Madrid in September 2004. Cruise is one of the world's most prominent Scientologists. "What I believe in my own life is that it's a search for how I can do things better, whether it's being a better man or a better father or finding ways for myself to improve," Cruise told Playboy magazine. "Individuals have to decide what is true and real for them."

Miscavige speaks during the inauguration of the Madrid church in September 2004.

Scientology made headlines in June 2005 when Cruise got into a heated debate with "Today" host Matt Lauer over psychiatric drugs. The Church of Scientology's website says that "the effects of medical and psychiatric drugs, whether painkillers, tranquilizers or 'antidepressants,' are as disastrous" as illicit drugs.

Actress Kirstie Alley and actor Tait Ruppert perform during the Church of Scientology's Christmas Stories XIV benefit in December 2006.