The former Australian rugby player was fired from the sport earlier this year after a comment on social media saying 'hell awaits adulterers, drunks and homosexuals.'
Speaking to members of Sydney's Truth of Jesus Christ Church on Sunday, Folau addressed the issue of children having the freedom to change gender as an example.
He said: "You see in today's youths and everything, they are allowing young kids in primary school to be able to have the permission to change their gender if they want to by taking away the permission of their parents.
"Now they are trying to take control as a government to make those decisions for young kids who are basically 16 years old or younger, they don't even know what they are doing.
"This is what the devil is trying to do, to instill into the government, into this world, into society, and it is slowly happening."
Folau is currently in the process of suing bosses at Rugby Australia on the grounds of religious discrimination.
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