May 5, 2010 -- 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."
Westboro Church Responds to Abuse Allegations
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.
Phelps-Roper said her brother was lying.
"Now he quit preaching and went to meddling," said Phelps-Roper. "The scripture says for children to be spanked. But with respect to spouses, wives -- you know I am married -- it says, 'Husbands, love your wives and treat them like you treat your own body.' That is the standard and that is what we live by.
"[Nate] lied when he said my dad beat on my mom," said Phelps-Roper. "He lied."
In the Phelps household, Nate Phelps said, children were also terrorized by their father's graphic depiction of the hell they faced if they did not behave.
"It was a very literal translation of a lake of fire," said Nate Phelps. "The worm that eats on you that never dies, the wailing and gnashing of teeth. It was a literal and agonizing concept of hell."
Fed up with his father's rage, Nate Phelps left home the very moment he legally could.
"I left the night I turned 18, literally at midnight," Phelps said. "I knew I was going to do it when I turned 15 or so, and I bought a car when I was 17, hid it, no one knew it was mine, packed my stuff up and at 11:30 on the night of my 18th birthday I backed it into the driveway and loaded it up and went inside, waited for the clock to hit midnight and then I left."
Last weekend, Nate Phelps -- now a husband and father -- returned to Topeka, the featured speaker at a rally in support of gay rights.
His homecoming was bittersweet. Phelps is among four of the 13 Phelps children who've severed ties with their family.
"There is a lot of anger from them for what I have done," Phelps said. "They call me a rebel and a traitor and you can't take that in without feeling some feelings. It's a mixed bag."
"He grew up living and learning the world of God," said Phelps-Roper. "And the Scripture says that when you walk away, there is no hope for you."
Westboro's remaining followers -- numbering fewer than a hundred -- are nearly all members of the extended Phelps family. Its leaders live at a walled compound in Topeka, flanked by upside-down American flags. It's less a church than a family group, dominated by one man's rage.
"There are about 80 percent [of church members] who are related by blood or marriage," said Phelps-Roper, "kind of like 100 percent of those who were on the ark when God sent the other 16 billion straight to hell."
In the church's eyes, every calamity -- 9/11, the Iraq war, the West Virginia mining disaster -- is evidence of God's wrath. These days it's the Gulf oil spill.
"Oh my gosh, it's an awesome God-smack," Phelps-Roper said of the spill.
Whether the church's protests at funerals are free speech or intentional cruelty will be argued before the Supreme Court this fall.
"They have a right to say what they want to say, they have a right to say it publicly," said Nate Phelps. "Where I would draw the line, and I hope this is what the Supreme Court does, is to say they don't have an absolute right to when and where. ... They are strangers standing outside that church as I am burying my son. Who are you to tell me how I was, or what I may or may not have done to cause this? That is evil, that is hateful."
So, after years on the sidelines, Phelps is going public against the Westboro church, and what it stands for. It's his way of atoning for the evil, he believes, that his own troubled family has inflicted.