The mother of a World Cup Wallaby infiltrated Israel Folau's church to reveal the "truth" about its teachings.
Helen Petaia, who used the name Josie Benc during the ruse, is the mother of Jordan Petaia who made his debut for the Wallabies against Uruguay in Japan.
The Herald Sun said it obtained correspondence between Petaia and Folau's 20-year-old cousin Josiah, who recently joined the Truth of Jesus Christ run by Israel Folau's father.
As part of her undercover investigation, Petaia also travelled from her Queensland home to attend a prayer meeting at the church in Sydney. She obtained "evidence" but would not say if she recorded anything.
The revelation Helen Petaia was behind the sting hasn't been well received in the Wallabies camp at the World Cup, news.com.au reports.
A source told The Australian newspaper that Folau had been "inundated with messages of support" from his former teammates, which expressed their "utter disbelief" at the "extreme lengths" she had gone to, it reports.
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Folau was axed by Rugby Australia because of homophobic media posts linked to his religious beliefs. The star fullback and winger is now suing RA for $10m.
Part of Petaia's motivation was to inform the Australian Christian Lobby – which raised money for Folau's legal expenses – about what his church believed in.
She had not informed Jordan about her actions, but was concerned that he and other young people would be influenced by Israel Folau's star power.
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She focused on the topic of litigation in the correspondence with Folau's s cousin.
"What does the bible say about suing people?" she asked.
"I wonder if this is something Jesus would ever consider doing.
"Your cousin Israel seems not to understand forgiveness and demonstration of the love of Jesus, he is behaving just like non-believers even though he says he is standing up for all people of faith."
Petaia also wrote: "Why take all that money from Rugby Australia and then destroy the livelihood (sic) of the players he says he cares about?"
Petaia said she was "gutted" that Folau was not still playing for the Wallabies.
"It's just a tragedy on so many levels," she said.
Petaia has been in the headlines previously, successfully fighting a tax bill which had crippled her small business.
Folau is suing RA and the NSW Waratahs for unlawful dismissal, claiming his firing earlier this year over the social media messages was because of his religion.
In one April post, Folau claimed transgender people were evil and should repent while another paraphrased a bible passage saying "drunks, homosexuals, adulterers, liars, fornicators, thieves, athiests and idolators" would go to hell unless they repented.
It was the second time he'd been pulled up for the same conduct, after it was revealed he offered to walk away from the sport and his contract over similar posts in April 2018.
RA and the Waratahs filed their defences to Folau's allegations in the Federal Circuit Court last month, revealing Folau conceded before a tribunal in May that his posts had breached the sport's code of conduct.
Faced with his concessions and refusal to remove the posts, the tribunal had little choice but to direct his contract be terminated, RA claims.
It says it's "remarkable" Folau now claims his posts did not breach the code and that he also conceded the posts had the potential to damage RA's relationship with sponsors and knew transgender and homosexual people may have been offended.
Folau claims his sacking was on the basis of his religion and has meant he can no longer play rugby union at an international level.
- Additional reporting: news.com.au