Parents at a Catholic high school are outraged their teenage children have been "forced" to write an assignment in advocacy of outspoken athlete and devout Christian Israel Folau.

As the former player battles Rugby Australia and the NSW Waratahs over his unceremonious sacking, students at St Patrick's Marist College in Sydney's northwest were told to support him.

In the video above: The latest on Folau's court feud

An assignment given to Year 9 students encourages them to "express their deep concern" for the protection of freedom of speech.

"Dear Member of Year 9," the assignment letter, signed off from "The Religious Education Year 9 Team", opens.

"We are sure you have heard through media and social forums the plight of Religious Freedom and Freedom of speech which is being depleted in our Australian society.

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"Recently Israel Folau, as noted in the news reports, has become the most discussed and divisive figure in Australia in recent weeks."

The letter goes on to question whether Australians should "have the right" to voice opinions on "individualities, beliefs and faith".

"Your mission is to present to your Local Member of Federal Parliament, a letter expressing deep concern for the future of protection of religion (sic) freedom and freedom of speech."

The letter sent to students from St Patrick's Marist College. Credit: Supplied

Parents are up in arms over the assignment.

One father, who asked to remain anonymous for his daughter's sake, questioned why Folau would even be a topic.

"Why would they even mention his name after the things he said that have put vulnerable teens at risk," he said.

"My daughter is really upset and is afraid to speak out about it at her school."

In the video below: Folau commences legal action

Play Video Israel Folau has commenced legal action against Rugby Australia and the Waratahs for unfair dismissal. Israel Folau has commenced legal action against Rugby Australia and the Waratahs for unfair dismissal.

Relieving Executive Director of the Catholic Education Diocese of Parramatta told 7NEWS.com.au it had been made aware of parents' concerns.

"A number of the sentiments in the covering letter for the assignment do not represent the views of the Diocese of Parramatta, its schools or Marist Schools Australia," she said.

"Catholic Education Diocese of Parramatta would like to apologise to students and parents for any concern created by the task and associated communication to students about these matters.

"The assignment has been withdrawn and students will be given the opportunity to complete a new assessment that is consistent with contemporary approaches to learning and teaching."

Israel Folau is taking Rugby Australia to court for unfair dismissal. Credit: AAP

The assignment was prompted by Folau's ongoing stoush with the Australian rugby sporting body, brought on by the termination of his contract.

It was torn up in May after an inflammatory social media post condemned "drunks, homosexuals, adulterers, liars, fornicators, thieves, atheists and idolaters" to hell unless they repented.

He has repeatedly stood by the post, saying it is his belief as a practising Christian that the post was factual.

Chief Judge Will Alstergren encouraged Folau and Rugby Australia to settle the dispute via mediation on December 13.

However, should mediation fail, it's likely to go before a court again in February next year.