"HELL", Folau responded. "Unless they repent of their sins and turn to God."
The Waratahs ace has a history of bigoted statements on social media. Ahead of Australia's marriage equality survey last year, Folau tweeted that "I love and respect all people for who they are and their opinions. But personally, I will not support gay marriage."
In 2014, Rugby Australia introduced an "inclusion policy", which stated that "There is no place for homophobia or any form of discrimination in our game and our actions and words both on and off the field must reflect this."
A Rugby Australia spokesman told the Sydney Morning Herald the body wouldn't comment and that Folau had deleted the comment.
It was still visible on Wednesday evening, however.
Folau, who has played 62 tests, is easily Australia's highest profile rugby player.
He is off contract at the end of this season.