Coalition MPs Dean Smith, Trent Zimmerman, Tim Wilson, Trevor Evans and Warren Entsch. Credit:Alex Ellinghausen "None of the other bills that have ever come before the Parliament - we've had in excess of 15 of them - none of the other bills have more comprehensively dealt with the issue of religious freedoms or religious protections," Senator Smith told ABC's Insiders on Sunday. "Now, this is important because there might be some people in my own party that would like to legislate for same-sex marriage but want to be satisfied that those religious freedoms will be in place. This bill does that. "People cannot be guaranteed that if a future Labor government is elected, these religious freedoms will be there." Under the bill, both religious ministers and civil celebrants who refuse to marry same-sex couples will be protected from legal action. The bill will create a new category of "religious marriage celebrants" who can legally refuse to officiate a same-sex ceremony.

Liberal senator Dean Smith says a postal plebiscite on same-sex marriage would be 'corrosive'. Credit:Philip Gostelow But business owners and service providers such as bakers, florists and photographers will need to prove they are linked to a "religious body" to reject a same-sex wedding. While Senator Smith was the key architect of the bill, he says it is important for its "moral authority" that it is introduced in the lower house. Liberal MP Trent Zimmerman is working on the bill with Senator Dean Smith. Credit:Alex Ellinghausen But it appears increasingly likely the party room will back the idea for a non-binding postal vote on the issue, as advocated by conservative Immigration Minister Peter Dutton.

But Senator Smith says that would be even worse than the original plebiscite proposal, costing up to $100 million but lacking in any force or authority. It would disenfranchise younger voters and Australians overseas, and potentially breach the constitution, he said. A postal vote would likely be struck down by the High Court unless it was underpinned by specific legislation - which would almost certainly be rejected by the current Senate - according to legal advice obtained by marriage equality advocates. The Parents and Friends of Lesbians and Gays group say it will not hesitate to take the government to court based on the advice prepared by Ron Merkel QC and Christopher Tran. Spokeswoman Shelley Argent said: "Some in the government are so intent on continuing the discrimination of LGBTI people they are now stooping to un-constitutional practice". If the Liberal party room does not back their bill the five rebel MPs are considering a high-stakes strategy of crossing the floor to support a motion to bring on debate.

Mr Zimmerman said that would be "a very serious decision" but did not rule it out on Sunday. He too hopes the religious exemptions in the private members' bill will persuade others to support a free vote. "We need to a find a way to get some finality on this issue," he told Sky News. Loading Opposition frontbencher Tony Burke says even if the government splits Labor "will not use this issue as an issue of confidence in the government - in no way, shape or form". Long-time marriage equality advocate and spokesperson for just.equal, Rodney Croome, said: "A postal vote will not be representative of the whole community, will not be binding on politicians and is just another desperate delaying tactic. It will also be a platform for fear-mongering and hate against LGBTI Australians."