They are widely despised. The fringe fundamentalists from Westboro Baptist Church in Topeka, Kansas, have become infamous by picketing the funerals of U.S. soldiers. Their claim: that God is killing U.S. troops to punish American tolerance of homosexuals.
"I think it's wrong, it's evil," Nate Phelps told "Nightline." "When they protest at people's funerals, they defy and deny everything that we consider decent and proper in our society."
Last weekend, Nate Phelps returned to face the family -- and church -- he now loathes. He broke away more than 30 years ago.
Members of the church stand outside soldiers' funerals holding signs that say things like "God loves dead soldiers."
"For me, that is the definition of evil," said Phelps. "They are so calloused about human emotions and the notions that we have about social etiquette, and they laugh at it. They laugh at the pain of other people."
Phelps is the sixth of 13 children. His father, Fred, now 80, is a disbarred lawyer and fiery preacher known for his lifelong rants against gays, Jews, Catholics and anyone else who doesn't share his views.
What's not well known, Nate Phelps told us, is the brutality and abuse that he says Fred Phelps inflicted upon his own family.
Phelps said his father would beat his young children with a barber's strap.
"He used it so frequently that the ends of it frayed, so you had this kind of cat o'nine tails whipping around, and it would open the flesh on the other side of the hip," said Nate Phelps. "So it was doing that kind of damage."
As the kids got older, Phelps said, his father would beat them with the handle of a mattock, a farm tool similar to a pickax.
"It's about four feet long and it's a solid, long, heavy piece of wood," said Phelps. "He would go down the back of the legs and up to the lower back, and when he was really angry and raging he would use it to hit you with the arms. On one occasion I can remember being hit with it in the head and it split my scalp.
"And his fists... there were times that he would be raging, and he would spit into his fists. He would be completely out of control and it could sometimes last for an hour. Going back and forth between physical violence and screaming Bible verses and berating the child."
We contacted the Phelps family at the compound where they live in Topeka, but Fred Phelps would not comment.
So we asked Fred Phelps' daughter, Shirley Phelps-Roper, a lawyer who serves as the church spokeswoman, about her brother Nate's allegations.
"He spanked [Nate], he spanked all of his children," Phelps-Roper said of her father. "Sometimes with a strap, until you got so big. A strap on a kid who is 12 or 13 years old?"
We asked whether it was true that Fred Phelps used a strap first and then a wooden handle.
"Exactly," said Phelps-Roper, "...and let's be sure we call it what it was, a paddle."
Not even their mother -- now 84 -- avoided physical abuse ... or the fury of Fred Phelps, according to Nate Phelps. He claims that his father beat his mother.