>> 12 years. >> reporter: ron miscavige, david miscavige's father is speaking out for the first time exclusively to abc news. you have written a whole book about your son, and you've called the book ruthless. it's a pretty damming charge to level against your own child. >> he wasn't always that way. >> reporter: roin miscavige said he wrote the book because of a policy called disconnection which he says tore his family and many others apart. >> i raised him and to come to this, what the hell is this? it's nuts. >> reporter: the church says ron's book co-written by a former church member is filled with half truths and outright lies. >> it's in my view, a literary forgery. >> reporter: scientology granting us a rare interview with attorney for the church. >> reporter: what has david miscavige's response been to the book? >> on a personal level, i think he's very sad his father would do this. there seems to be no explanation exempt his father is trying to make a buck. >> reporter: while the church is attacking him, he's getting support from a prominent voice. >> i'm going to get there f

what has david miscavige's response been to this book? >> well, i think he's -- on a personal level i think he's -- he's 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 of his name. >> reporter: this unusual family history and subsequent family feud was set in motion in 1968, when ron first hears the word scientology at a business meeting. what was it about the word scientology that got you so interested? >> i don't know. but it did. all i heard was scientology, and i thought, what is that? >> reporter: ron soon learns that scientology is a new religion founded by the science >> there are certain evils in society which definitely should cease, and we're taking responsibility for them. >> so i went to a place where there was a guy who was teaching scientology. he would do drills to teach you better communication. >> reporter: so it was useful salesman. >> yeah. >> reporter: and also as a guy who was in a marriage that had a >> oh, yeah, yeah. >> rep

and that's how they operate. >> reporter: coming up -- it's miscavige versus miscavige as ron's other some of the things your daughter's saying. quote, "our father beat our mother senseless in drunken tirades, averaging two violent attacks with his fists per week." >> it's such a lie. it's, it's beyond belief. >> reporter: and "20/20" tries to speak to the man at the center of the storm, david miscavige himself. >> we were hoping to talk to david miscavige if he's here today? >> reporter: stay with us. see what i mean? it checks you into your flight. ooop, your phone! it pays for stuff like... (mouth full) doughnuts. how about chew then talk. it unlocks things for you. it signs documents for you. hey, you bought a boat! i bought a boat! i just said that. and it does this. yeah, it starts your car. so now we're just starting cars with our fingerprints. just. whoa. my son and i used to watch the red carpet shows on tv now, i'm walking them. life is unpredictable being flake free isn't. because i have used head and shoulders for 20 years. used regularly, it removes up to 100% of flakes k

now, new claims tonight about its powerful leader, david miscavige. they come in a new book, written by david miscavige's own father, after he broke away from scientology and from his own son. abc's dan harris, with the father and the family now ripped in two. >> reporter: ron miscavige, now breaking ranks and publicly criticizing his own son, the powerful leader of the church of scientology, david miscavige. >> if you are a scientologist, you are one of the relative few that hold the answers in your possession that all humankind depend upon. >> reporter: ron was in the church for decades, but has now left and written a book, which he discusses in an exclusive interview with abc news. you have written a whole book about your son, and you've called the book "ruthless." >> yeah. >> reporter: that's a pretty damning charge to level against your own child. >> he wasn't always that way. when he was a kid, i am telling you, he was a lovable kid. >> reporter: a lovable kid who, according to his dad, let the power of being at the helm of this wealthy, celebri

david miscavige sits atop one of the most controversial churches on earth and now his own dad has quititten a book about his time in the church. scientology is hitting back hard and now leah remini is enterin the fray. this morning, leah remini -- >> you are unbelievable. >> reporter: the former star of "the king of queens" going to bat for a fellow ex-scientologist. >> he has a right to tell his story. >> reporter: ron miscavige, the father of the powerful leader of the church, david miscavige. >> if you were a scientologist you are one of the relative few that hold the answers in your possession that all humankind depend upon. >> reporter: david miscavige bears the title of chairman of the board or cob and he was the best man at the wedding of tom cruise and katie holmes. >> so i say to you, c.o.b., we are lucky to have you and thank you very much. >> reporter: when word hit that david miscavige's own father, the now 82-year-old ron miscavige had left the church after decades of service, leah remini says it spread like wildfire. >> i tracked him down. i called him and i offered my su

david miscavige. >> you are one of the relative few that hold the answers in your possession that allnd upon. >> reporter: ron was in the church for decadeses but left and written a book which he discusses in an interview with abc news. >> you have written a whole book about your son and you called the book "ruthless." >> yeah. >> it's a pretty damning charge to level against your own child. >> he wasn't always that way. when he was a kid, i am telling you, he was a loveable kid. >> reporter: a loveable kid who according to his dad, let the power of being at the helm of this wealthy celebrity studded church go to his head. >> i say to you sir, we are lucky to have you and thank you attacking the book arguing it was co-authored by a noted critic of church management and is laden with outright lies. >> it is not a memoir. it's in my view a literary forgery. >> he has a right to tell his story but leah remini. >> you are unbelievable. >> reporter: the former star of the king of queens" who can herself was criticized by scientology after she quit the church and wrote a book is, going to b

but playing the horn, ron miscavige, his dad. what's the relationship? >> tom cruise thinks that david is the top spiritual being on the planet. >> reporter: he's speaking out about why he decided to leave the church, and write a book about his own son called "ruthless." >> power tends to corrupt. that taste of power, i think, is what changed david. >> reporter: he said one night, david gave him an extended tongue lashing with other scientists look on. >> he's backstage, tearing me apart for 55 minutes. cursing, screaming, yelling at me. >> reporter: he says his life in the sea org became unbearable because of crushing workloads and little sleep. the church is pushing back. >> they may work hard, but they enjoy it. >> reporter: and letters from ron's former band mates calling him lazy and a disgusting pig. and ron said if he was that bad, he would have never been put front and center with tom cruise. >>> and later tonight, on "20/20," more on the story, 10:00 p.m. tonight right here. >>> much more to come on "world news tonight" tonight. new information

that's ron miscavige, david's dad. who's now going public. what's the relationship? >> tom cruise thinks that david is the top spiritual being on the planet. they're, like, the best of buddies. >> reporter: he's speaking out about why he decided to leave the church, and write a book about his own son called "ruthless." >> power tends to corrupt. and absolute power corrupts absolutely. that taste of power, i think, is what changed david. >> reporter: he said he experienced his son's temper one night. david gave him an extended tongue lashing with other scientologists looking on. >> he's backstage, tearing me apart verbally for 55 minutes. cursing, screaming, yelling at me. >> reporter: he says his life in the sea org became unbearable over time because of crushing workloads a rigid lifestyle, and little sleep. the church is pushing back. >> they may work hard. they may work really long hours, even more than we do, but they enjoy it. >> reporter: the church sent us letters from ron's former band mates. calling him lazy, a poor musician, and a disgusting pig. and ron sa

. >> reporter: ron miscavige, now breaking ranks and publicly criticizing his own son, the powerful leader of the church of scientology, david miscavige. >> if you are a scientologist, you are one of the relative few that hold the answers in your possession that all humankind depend upon. >> reporter: ron was in the church for decades, but has now left and written a book, which he discusses in an exclusive interview with abc news. you have written a whole book about your son, and you've called the book "ruthless." >> yeah. >> reporter: that's a pretty damning charge to level against your own child. >> he wuls aunt that way. when he was a kid, i am telling you, he was a lovable kid. >> reporter: a lovable kid who, power of being at the helm of this wealthy, celebrity-studded church, go to his head. >> and i say to you sir, cob, we are lucky to have you and thank you. >> reporter: scientology is attacking the book, arguing it was co-authored by a noted critic of church management, and is laden with outright lies. >> it is not a memoir. it's, in my view, a literary forgery. >> he has a right

that older gentleman playing the horn, that's ron miscavige, david's dad, who now much to the chagrin decided to step out and play so solo. >> what's the relationship between your son and tom cruise? >> tom cruise thinks that david is the top spiritual being on this planet. >> the top spiritual being on the planet. >> ron miscavige now 80 is now speaking out about why he decided to leave the church and write a book about his own son called "ruthless". >> power tends to corrupt, and absolute power corrupts absolutely. that taste of power i think is what changed david. >> reporter: ron spent threely three decades working in the religious order of the church where he says he witnesses hi son's volcanic temper. >> david is backstage literally tearing me apart verbally for 55 minutes, cursing, yelling, screaming at me. >> reporter: for six years ron lived on a sprawling steintology base in hemmette, california, known as gold. >> it got worse and worse and worse. >> reporter: ron blame his son for what he calls an intensely stressful atmosphere at the base and says overtime the crushing wor

david miscavige hasn't spoken to since 1992 but now his father is speaking out against him. >> you called

david miscavige hasn't spoken to since 1992 but now his father is speaking out against him. >> you called the book ruthless. >> yeah. >> that's a damming charge against your child. >> he wasn't always that child. >> ron miscavige said it's cost his relationships with his own daughters and tonight former signtologists complain their families won't speak to them and

david miscavige hasn't spoken to since 1992 but now his father is speaking out against him. >> you calledformer signtologists complain their families won't speak to them a

that older gentleman playing the horn, that's ron miscavige, chagrin of the church has decided to step out and play solo. what's the relationship between your son and tom cruise. >> tom cruise thinks that david is the top spirit cal being on this planet. >> the top spiritual being on the planet. >> they're like the best of buddies. >> reporter: in an exclusive interview ron miscavige now 0 speaking out about why he decided to leave the church and write a book about his own son called "ruthless." >> power tends to corrupt and absolute power corrupts absolutely. that taste of power i think is what changed david. >> reporter: ron spent nearly three decades working in the seaorg, the religious order of the church where he witnessed his son's volcanic temper. >> david is backstage literally tearing me apart verbally for 55 minutes cursing, yelling, screaming at me. >> reporter: for six years ron lived on a sprawling sinai peninsula base in california >> it got worse and worse and worse. >> reporter: ron blames his son for what he calls an intensely stressful atmosphere at the base and says