Israel Folau is taking Ruby Australia (RA) to court following its decision to terminate his contract after he posted a picture to Instagram saying that "hell awaits" homosexuals and others.

The former Wallabies fullback, 30, was dismissed last month after being found guilty of a "high level" breach of player conduct by a three-person panel. 

At the time, he said that although he would not appeal RA's decision to tear up his $4m contract, he had not ruled out further legal action. 

He is now moving ahead with legal proceedings, saying that "no Australian of any faith should be fired for practicing their religion".

Folau was sacked after posting an image that said "hell awaits" for "drunks, homosexuals, adulterers, liars, fornicators, thieves, atheists, idolaters". 

The devout Christian accompanied the post with his own personal reflections, telling his Instagram followers: "Those that are living in Sin will end up in Hell unless you repent. Jesus Christ loves you and is giving you time to turn away from your sin and come to him." 

The Sydney Morning Herald reports that Folau's legal representatives have filed an application with the Australian Fair Work Commission seeking recognition of unlawful termination on the grounds of his religion. 

Section 772 of the Fair Work Act prohibits the termination of an individual's employment on the basis of their religion.

In a statement from Folau's legal representatives, the player thanked his supporters and said that freedom should apply to all Australians. 

"I will forever be grateful and proud to have played the sport I love for our nation. Ours is an amazing country built on important principles, including freedom of religion," he said.

"A nation made up of so many different faiths and cultural backgrounds will never be truly rich unless this freedom applies to all of us.

"The messages of support we have received over these difficult few weeks have made me realise there are many Australians who feel their fundamental rights are being steadily eroded."

Prior to his dismissal, Folau had been expected to represent Australia in the Rugby World Cup in Japan later this year. 

In addition to losing his lucrative contract with RA, the star player was also dropped from sponsorship deals by Land Rover and athletics brand Asics.

The suit filed by Folau says that he is seeking "substantial remedies" for lost salary and sponsorship deals, as well as "civil penalties". 

"The termination has cost Mr Folau the best years of his rugby career, participation at the Rugby World Cup, the chance to become the greatest Wallaby try-scorer (a decades-old record he was likely to break), and the associated exposure and opportunities," the application states.