Folau's four-year, multi-million dollar deal was cut short after an independent panel backed RA's position that the comments he made in April were in breach of their Professional Players' Code of Conduct and warranted his sacking rather than a fine or suspension.
The devout Christian said on his Instagram account that "hell awaits" for "drunks, homosexuals, adulterers, liars, fornicators, thieves, atheists, idolaters".
The sacked rugby star has taken his case to the Fair Work Commission and is seeking up to $10 million (£5.5m) in damages for unlawful termination.
"No Australian of any faith should be fired for practising their religion," Folau said in a statement.
His lawyers have stated that it is unlawful to terminate employment on the basis of religion.
The chairman of the Australia National Rugby League Commission, Peter Beattie, reaffirmed on Wednesday that the NRL would not allow Folau back into the game under any circumstances.
Folau's brother also quit the Waratahs over the issue on Thursday.
Stay up to date with the latest news stories from a Christian perspective. Sign up to our daily newsletter and receive more stories like this straight to your inbox every morning.