Billy Vunipola, who 'liked' fellow Christian Folau's message on Instagram (below), wrote a detailed response, having received three phones calls asking him to 'unlike' the post.
It comes after Rugby Australia said it intends to terminate Folau's contract, claiming he's entitled to his religious beliefs but it's the way he expresses them that is the problem.
Folau has received a huge backlash with the accusation that he's homophobic.
Writing on Instagram, Vunipola said he was forced to respond when people were insulting his beliefs.
"There just comes a point when you insult what I grew up believing in that you just say enough is enough," he said. "What he's saying isn't that he doesn't like or love those people. He's saying how we live our lives needs to be closer to how God intended them to be.
"Man was made for woman to pro create. That was the goal, no? I'm not perfect. I'm at least everything on that list at least at one point in my life. It hurts to know that. But that's why I believe there's a God. To guide and protect us and forgive us our trespasses as we forgive those who trespass against us."
Vunipola has previously spoken about the impact his faith has on his life. Speaking to Engage 2015, he said: "Knowing that Jesus is with me makes me a stronger person, makes me a more confident person.
"Whatever I do, try to do, even if it doesn't come off, I'll always have God or Jesus to lean back on, and I know if it didn't go my way there must be a reason. There is always a reason."
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