Westboro followers mainly consist of Fred Phelp's children, grandchildren and now great-grandchildren. The families live on the same street, their houses encircled by a tall fence, and share a backyard. On the one hand Phelps-Roper, one of 11, experienced many elements of a conventional childhood — games nights, family barbecues and pool days, chores and loving parents. But obedience and discipline reigned supreme and rule-breakers were condemned and punished harshly. Meaningful relationships with outsiders were banned. Phelps-Roper picketed her own public school during lunch breaks; her 19-year-old brother left the church in the middle of the night and was hardly spoken of again; and she shared her dinner table with an endless stream of journalists. Megan Phelps-Roper left Westboro Baptist Church in 2012. A "cherished daughter", Phelps-Roper became the church's voice on Twitter, posting comments such as “Thank God for aids!” but also developing a reputation for using wit and humour to engage in biblical combat. It was engagement with her "enemies" and their kindness that gradually revealed to her the "logical blindness" in Westboro's beliefs. Once she started to see the contradictions within the church's doctrine, she couldn't look away. To her, the most grievous was the church's use of hate, a revelation compounded by the church's harsh disciplinary treatment of her mother, sister and cousin, the introduction of restrictive new rules and a change in leadership. "With stark clarity I understood that whether the church was wrong or right, I was a monster," Phelps-Roper writes. In November 2012, Phelps-Roper, then 26, left the church with her sister Grace. So entrenched was a bible verse used as an attack on those who absconded – oh that mine adversary had written a book – that she never wanted to write about her experience. Unfollow instead started as an essay for her husband, Chad, one of the outsiders she met online who helped her question her beliefs. The wounds were fresh and she found it too painful to look at the dozens of family videos and photographs she had copied before she left, aware she might never see her family again. Phelps-Roper says she obsessively checked Westboro's social media feeds in the months after she departed, but when she finished writing she discovered it had been weeks since she last sought to look.

"Writing definitely allowed me to process things and to let go of some of the really painful aspects. I had been so terrified of forgetting, I think that was a big part of it, so to now to have spent all of this time writing it out, I have this record now and I don’t have to hold it to me quite so tightly." Losing her religion: Author Megan Phelps-Roper. I hope there will be something in it that will reach them. Westboro usually tries to erase the existence of ex-followers – they went out from us but were not of us – but the exception is when they get public attention, in which case the church will try to co-opt it and redirect it to their message. Phelps-Roper is prepared for the church's wrath. She expects her book will be discussed within Westboro, although they might not want younger members to read it. Followers will claim she is corrupted and evil, or pity her loss of faith. She still reaches out to her family in the church, privately and publicly, but rarely gets a response. Letters, postcards, cupcakes and birthday presents are posted. She can't imagine a time when she would stop trying to contact them. "To know how I was changed, how my mind and heart were changed, the idea of not doing the same thing for the family who loved me and raised me and exacted so much time, love and patience into me, the idea of not doing that for them doesn’t occur to me."

When we talk, Phelps-Roper, who has a one-year-old daughter, is planning to send a copy of her memoir to her parents. It's dedicated to them: "I left the church, but never you – and never will." "I don’t have any expectation that they will read the book and then just decide to leave and give it all up I don’t have that expectation or hope even," Phelps-Roper says. "I hope there will be something in it that will reach them and even if it doesn’t cause them to leave, if it causes them to think twice about something, if it causes them to moderate their position in anyway, I would be extremely happy." There are currently about 80 members of the church, almost the same number as when Phelps-Roper left. Fred Phelps died, stripped of his role as pastor and church membership, in 2014 aged 84, after apparently coming to see Westboro as cruel and unmerciful. Another of Phelps-Roper's siblings and other cousins have also departed the church. Non-believers were always painted as evil, and one of the great discoveries of leaving the church for Phelps-Roper was the kindness of outsiders. It’s not just Westboro. There are very common human forces that made them what they are.

"We try to support each other, not just emotionally but practically and financially. There’s a learned helplessness for a lot of people who are leaving Westboro because you’re not allowed to have any kind of independence when you are there so a lot of people don’t have practical life skills." Phelps-Roper continues to keep abreast of developments within Westboro, aware that if she wants to change the minds of followers she has to know what they believe The biggest encouragement that change is possible, she says, is that Westboro has stopped praying for death and have replaced their hateful signs. Loading The ex-cult girl is a title that Phelps-Roper knows she can't avoid. But she's been channelling her experience of deradicalisation and the importance of kindness into TED talks, speaking events, documentaries and working with academics and law enforcement agencies. Her new faith is in the power of hope, reserving judgment, kindness and the power of reaching across ideological divides. "I feel like I was transformed by the kindness of people who had every reason to show me cruelty and the transformative power of their decision to treat me like a human being, that was so huge, that anytime somebody wants me to talk about that I feel like I absolutely want to do that.

"I am looking forward to pivoting away from having it be so intensely about my own experiences because I think the themes here are so much bigger. They are not just me. It’s not just Westboro. There are very common human forces that made them what they are. I am really interested in studying those forces and seeing how they manifest in the lives of other people and what I can do to help other people dealing with similar situations." Unfollow is published by Hachette at $32.99. Megan Phelps-Roper will join Louis Theroux as a guest on his Australian tour next year.