Israel Folau used a sermon in his church in Sydney to describe homosexuality as a sin and to criticize young people who are allowed to "change their gender".
In a video posted on his church's Facebook page, the former rugby star claimed that the devil was behind permission to decide if they wanted to change sex.
"They are allowing elementary school children to be able to have sex change permission if they want by removing their parents' permission," Folau told the truth of the church of Jesus Christ in Kenthurst.
"Now they are trying to take control of a government to make those decisions for kids, they basically have 16 or less, they don't even know what they are doing … this is what the devil is trying to instill in this government, in this world, in society, and it is slowly happening.
"The sad thing is because many people out there who are not Christians say bad things about the church, because many of the churches allow these things to happen.
"They say that a man and a man should be able to marry and there is nothing wrong with it. This takes the theme of pleasure to the man rather than pleasing God and defending the truth."
The Wallaby's former contract for $ 5 million rugby in Australia was ripped apart last month after it refused to write a post on Instagram citing biblical writings and saying "hell awaits" homosexuals and other sinners.
In the new video, Folau also criticized modern "westernized" churches and said that true believers in Christ "profess him wherever we go".
"We are too scared because we could be thrown out of our workplace or hunted somewhere because we are not loved or loved by those around us and we do not believe in the same thing we do?", He asked.
"You could be the only Christian reborn in that workplace, you may feel a little embarrassed with your work colleagues because they are in the world and you are not. We should feel blessed … because God has called us ".
Folau has started legal proceedings with the Fair Work Commission against Rugby Australia and is seeking up to $ 10 million in damages.