In an upcoming documentary, the son of Westboro Baptist Church founder Fred Phelps reveals the horrific abuse he and his siblings experienced under the tyrannical rule of their father.

In the documentary titled "Not My Father's Son," Nate Phelps says that he was both physically and mentally abused in the household headed by Phelps Sr., who founded Westboro Baptist Church in 1955. The film shows the inside workings of the church and documents Phelps' journey from his difficult childhood to his departure which cut him off from his family.

In the trailer for the film, Phelps paints a shocking picture of the kind of physical punishment he and his siblings experienced at the hands of their father.

"So, my father used what was called a "mattock handle." It was a large piece of wood about four-and-a-half feet long and it had about a thirteen, fourteen-inch circumference," Phelps says in a voiceover. "And he would swing that like a baseball bat when he was beating one of the kids. And he did it such that he would hit us five or ten times, and then he would scream at us about what we'd done wrong, and how we were going to go to Hell for it, and how God hated sinners, and in the Old Testament times I would have been taken out of the city gates and stoned because I was disobedient."

"This was the kind of rhetoric that we heard, and then he would go back to the physical beating and he would work himself up into this frenzy. And it would be bad enough that you literally couldn't sit down, or lie down on your backside for two or three days," he continued.

Co-directors Brad Johnson, Terrie Johnson, and Jason Badgett are raising money to produce the film via a Kickstarter page. Brad Johnson told The Daily Beast, "We've been doing this on our own time and our own dime. Now we're tapped out."

The filmmakers hope to provide hope to others growing up in abusive environments, as studies have shown that people abused as children are at a higher risk of growing up to be abusers later in life. "Nate's escape from the abusive and hateful environment in which he was raised coupled with his quest to break the cycle of abuse and hate for future generations create a poignant and powerful theme for the film," reveals the film's Kickstarter page.

So far, several members of the Phelps family have left the church. Earlier this year, Phelp's relative Zach Phelps-Roper also departed, saying he now "sees the world from so many different perspectives.