John Travolta on ‘The Forger,’ How Scientology Saved His Life

— -- Actor John Travolta has three words of advice for those who question his religion, Scientology: Read a book.

“You can read ‘A New Slant on Life.’ You can read ‘Dianetics,’” the actor said today on “Good Morning America,” referring to two books authored by Scientology’s founder, L. Ron Hubbard.

“I think if you really read it, you understand it,” he said. “But unless you do, you’ll speculate -- and I think that’s a mistake to do that.”

Scientology, which claims Tom Cruise as arguably its most famous member aside from Travolta, has been in the headlines this month after HBO aired a documentary, “Going Clear: Scientology and the Prison of Belief,” that made allegations about life inside the church, its practices and Hubbard himself.

“Sometimes, when something really works well it becomes a target,” Travolta said, without mentioning the documentary by name.

Travolta, 61, credited Scientology with saving his life and helping him save the lives of others.

“Forty years for me, I’ve been part -- and I’ve loved every minute of it, and my family has done so well with it,” said Travolta. “It’s a beautiful thing for me and I’ve saved lives with it. Saved my own life several times.”

“Through the loss of my son, it helped me every step of the way for two years solid, and here I am talking to you because of it,” Travolta told ABC News’ Amy Robach.

Jett, Travolta’s son with wife Kelly Preston, died in 2009 at the age of 16 after a seizure. The actor said he was forced to “reflect” on the painful experience while acting in his new movie, “The Forger.”

In the film, Travolta plays an art forger who gets out of prison to find his son dying of a brain tumor.

“I think you can’t help but have it reflect on your own life,” Travolta said. “I try to separate my art from my life sometimes when it’s that personal, but I believe that it’s hard not to, sometimes, have it reflect.”

Travolta said he traveled to Hong Kong to study oil painting for the film, had a professional painter with him on set in Texas and even painted a piece, himself, to truly “be in character.”

“I did it through half the film, I was working on it,” the “Grease” star said. “My idea was, in order to be in character, to feel the real pressure of trying to duplicate a famous painting -- and I just wanted to know what that felt like, so I tested myself.”

Travolta’s father in “The Forger” is played by “Sound of Music” star Christopher Plummer. Despite their shared musical film pedigrees, Travolta said, this was not a set where the pair sang and danced.

“We just found it very interesting that the thing we’ll most be remembered for are those two films, ‘Grease’ and ‘Sound of Music,’” Travolta said. “We have that in common, let’s say.”

"The Forger" opens nationwide and on-demand this Friday, April 24.