Scientology Leader David Miscavige's Father on David's Childhood, Why They Joined the Church Ron Miscavige remembers when he first introduced his son to Church practices.

 -- Ron Miscavige, the father of the Church of Scientology leader David Miscavige, remembers when he first introduced his son to Church practices.

David Miscavige was a 9-year-old boy at the time, his father said, and after David finished his first “auditing,” a kind of Scientology counseling session, Ron Miscavige said he saw something change in him.

“After 45 minutes, David walks out, smiling, bright,” Ron Miscavige told ABC News “20/20.” “[That moment] decided his life, and mine.”

For the first time ever, Ron Miscavige opened up about his experience as a former member of the Church of Scientology and his son David Miscavige in an exclusive interview with ABC News’ Dan Harris for a special edition of ABC News’ “20/20.” Ron Miscavige also talked about his new memoir, “Ruthless: Scientology, My Son David Miscavige, and Me,” out on May 3.

Although he used the word “Ruthless” to describe his son David in the title of his book, Ron Miscavige said, “He wasn’t always that way.”

“When he was a kid, I am telling you, he was a lovable kid,” he said.

In his interview with “20/20,” Ron Miscavige recalled the day in 1960 when the nurses brought his son David, his second child, out of the delivery room.

“He was kind of smiling with a bit of a scrunched-up face,” Miscavige said. “And I looked at him, I says, ‘Ah,’ you know, ‘This is your old man,’ you know, Gave him a kiss.”

The family lived in Willingboro, New Jersey at the time, where Miscavige and his then-wife Loretta raised their four kids -- the oldest Ron, Jr., David, Denise and the youngest, Lori. Ron Miscavige said David was a happy child but the “bane of his life” was dealing with asthma.

“He would get severe attacks,” he said.

David was an “excellent” student, Miscavige said, but he started getting into fistfights when he was a first grader.

“He enjoyed having a fight,” he said. “And I’m sure he instigated it… he’s a tough kid. I mean, for his size, he’s like a stick of dynamite.”

Miscavige also said that his son had a tendency to put others down.

“He would come home and start complaining about somebody and I would say, ‘Hey, come on, you’re like Little Bad News, what the hell is this?’ … and then he would knock it off,” Miscavige said.

Ron Miscavige said the family’s home life wasn’t the easiest and he admitted that he hit his then-wife and their kids.

“Marriage-wise, we didn’t have a great marriage at all,” he said. “We had strife, and there was some domestic abuse, which I don’t feel good about, and I don’t think you can make excuses for that, no matter what, or how much time goes by.”

The Church of Scientology told “20/20” that Ron Miscavige’s acts of domestic abuse are much more serious and frequent than he admits. The Church said Miscavige’s memoir is filled with lies and granted “20/20” a rare interview with Church lawyer Monique Yingling, who called the book “a literary forgery.”

“And the title of the book, ‘Ruthless,’ I mean, it couldn’t be a falser description of David Miscavige,” Yingling told “20/20.” “He’s a very compassionate, kind person.”

David Miscavige declined repeated requests from ABC News to comment on this story, but Yingling told “20/20” that, “On a personal level, I think he [David] is probably very, very sad that his father would do this.”

“There seems to be no explanation except that his father is trying to make a buck off his name,” she continued. “So I think there’s that level of sadness and I’m sure a sense of betrayal.”

Miscavige’s daughters declined to sit down for an interview with “20/20,” but through an attorney told “20/20” in a statement that they have cut off all ties from their father. They claim he was more violent with their mother and them than he admits, accusing him of striking them with his fists and his belt and saying, “Our father beat our mother senseless in drunken tirades, averaging two violent attacks with his fists per week.”

Ron Miscavige denies those claims. “That is a flat-out lie,” he said.

Ron Miscavige, a musician and a salesman, said he first heard about the Church of Scientology, a religion founded by the late science fiction writer L. Ron Hubbard, in 1968 at a business meeting. After he started looking into it, he said he found someone teaching Scientology in New Jersey and started attending meetings regularly.

Miscavige said Scientology resonated with him at the time and he began paying for “auditing” sessions, a sort of counseling that uses a Scientology device called an E-Meter. The process promises to release negative emotions and Ron Miscavige thought it was life-changing.

“I didn’t know what I was looking for, but I knew I was looking for something,” Miscavige said. “When I got into Scientology, I felt that I had found what I was looking for, which did have a lot of answers … on a basic life.”

Miscavige said he took his son David to his first auditing session in 1969, and afterwards, he said his son seemed elated and his asthma attacks lessened “considerably.”

When asked if he thought his son's asthma was linked to a psychological component, Miscavige said, “Of course, that’s what the auditing handled, the actual psychological phenomena of it.”

“I think it was at that moment that he [David] decided he’s going to do something with this,” he added.

According to Ron Miscavige, the whole family began studying Scientology, with David setting himself up as somewhat of a prodigy by the time he was a teenager. With his family’s consent, David left home at age 16 to join the clergy of the Church, known as the “Sea Organization” or “Sea Org.”

“He advanced very rapidly in the Church,” Miscavige said. “He really decided at a very young age to make it his career and his mission.”