Michael Kirby has blasted the Coalition for failing to release the Ruddock review, warning that secularism is at threat and Australians are right to be “suspicious” the government has not stated its plans on religious freedom.

The former high court justice told Radio National on Thursday it was “unusual in our information hungry society” that the Ruddock religious freedom report had not been released after five months. He also challenged the prime minister, Scott Morrison, for his decision to increase religious schools’ funding and over his comments about sexual diversity.

Kirby said the report had been handed to the Turnbull government in May and whatever it recommended “wasn’t enough to convince the Turnbull government to do anything, certainly for a long while”.

“What worries the secular members of our community … is that something has been cooked-up, it’s being designed to give a lot more power and maybe some more money to the religious organisations in society.

“It hasn’t been released up to now – now that’s a long time in Australian politics, we’ve lost another prime minister in that time – and therefore the mind gets a bit suspicious, I’m afraid.”

Kirby suggested concern was justified given “the background of billions of dollars handed out to the faith communities and religious organisations” in the Morrison government’s $4.6bn Catholic and independent schools package and the Coalition’s funding for the chaplaincy scheme, which he said “invades public schools with religious chaplains”.

Asked whether religious Australians were right to worry about the impact of same-sex marriage, Kirby said that people “generally accept what the majority in parliament decide” in a representative democracy despite there being “lots of things we don’t agree on in Australia”.

Kirby praised the concept of secularism – that in the public space “we respect all religions or no religion” – and warned it was “at risk” in both the United States and Australia, but Australia lacked the constitutional protection for secularism.

Asked what the Ruddock review was likely to find, Kirby said that there “are dangers in increasing the protections” for religious freedoms and noted that many submissions had asked for religious protections to be rolled back. Many LGBTI groups called for religious exemptions to discrimination law to be repealed.

Kirby said that some people argue “when religion enters the marketplace, when it’s involved in providing education, healthcare, aged care, then they’ve just got to comply with the principles of openness – secular principles – to respect people of religion and of no religion”.

Kirby noted that Morrison had “come out strongly in favour of further protections for religious freedoms” and had claimed to “love all Australians”, which “means of course that he loves LGBTIQ people”.

But Kirby noted Morrison had also said his “skin curled – a very vivid metaphor – when he heard that children in public schools were being educated in terms of respecting people of diverse sexuality”.

Kirby said sexual diversity was “just part of science, part of our nature”.

“If it’s being taught in public schools it’s simply telling children what they probably know already anyway, that there are LGBTIQ people in their midst,” he said. “If private and religious schools are not telling them that, then they’re letting them down in terms of their duty to look after all children in their care – especially if they’re receiving public money.”

The content of the Ruddock review is still largely unknown, although one panel member has suggested religious freedom may require only “slight tweaking” – implying it recommended only minimal change.

Morrison has called for “preventative regulation and legislation” to prevent religious people being discriminated against because of their beliefs.

“Why should you be denied a directorship or a partnership in a law firm or accountancy firm just because you happen to have expressed on Facebook or somewhere a particular religious belief?” Morrison said in September.

The independent candidate for Wentworth, Kerryn Phelps, has called on the Morrison government to release the Ruddock report before the 20 October byelection.

The attorney general, Christian Porter, has said the government has not released the Ruddock review because it is working on its response.

On 18 September the shadow attorney general, Mark Dreyfus, wrote to the government saying he was “deeply concerned” that it would not allow time for public consultation on the Ruddock review before announcing its response.

“There is no reason for the government to keep the Ruddock report secret any longer,” he said. “It is only fair that the Australian people, and interested groups in particular, are offered an opportunity to consider the report themselves.”