The dual international,who has 337,000 followers on Instagram,made the comment in reply to a question from another user on Tuesday,Folau's 29th birthday.
"@izzyfolau what was gods[sic] plan for gay people??"user Mike Sephton-Poultney said.
"@mike_sephton HELL... Unless they repent of their sins and turn to God,"Folau replied.
The exchange was picked up and shared on Twitter before going viral around the world. A Rugby Australia spokesman said Folau had deleted the comment,although it was still visible on part of Folau's profile on Wednesday afternoon.
It appears to be in contravention of Rugby Australia's inclusion policy,which was adopted in 2014 and states:"Rugby has and must continue to be a sport where players,officials,volunteers,supporters and administrators have the right and freedom to participate regardless of gender,sexual orientation,race or religion and without fear of exclusion. 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."