Labor is expected to finally confirm on Tuesday it will kill off the same-sex marriage plebiscite and vote against it in the Senate, after months of hinting and threatening to do so.

That formal decision, once ticked off by the ALP caucus, leaves the legalisation of same-sex marriage in limbo, with the government unlikely to allow a free vote in the Parliament, despite what some advocates of legal change may claim.

The Turnbull government's proposed amendments to the Marriage Act, which would only be implemented if the plebiscite went ahead and was passed, were due to be examined by a committee on Monday night.

It's understood these amendments include changes to the Act that would redefine marriage as being between two people, instead of a man and woman, would allow religious and civil celebrants to refuse to perform marriage ceremonies but there would no exemptions for other service providers from anti-discrimination laws.

Cabinet minister Simon Birmingham suggested on Monday night that a request from Labor to remove public funding for the "yes" and "no" campaigns for the plebiscite - a key sticking point - might be "reasonable ... and one we could consider ourselves".

However, such a move would create a firestorm of protest from conservative Coalition MPs and is unlikely to proceed.

Meanwhile, in a speech at the Hobart book launch last week of Stealing from the Child - the injustice of 'marriage equality' by Australian Marriage Forum president David van Gend, Senator Abetz said a campaign has been under way since the 1970s to deconstruct marriage and "rob it of its meaning".

"Ever notice how when some people go from the heterosexual to homosexual lifestyle they are able to be celebrated and honoured for their honesty and courage? They've come out," Senator Abetz said.

"Ever thought why there is no celebration for those that decide to go from the homosexual to heterosexual lifestyle? Are they not honest? Are they not coming out as well? And that is just one of the examples of the one-way traffic and bias from the media."

The conservative Tasmanian senator, a fierce opponent of same-sex marriage, warned that changing the definition of marriage is a gross injustice that would "steal from children", threaten Australian society and will do "irreparable damage to the next generation".

Senator Abetz's register of interests shows he has stepped up his support of bible groups, including continuing to donate to Bible League, which has promoted using bible teachings to treat mental illness, converting Muslims to Christianity to help end terrorism and demonic possession.

One film, published on the Bible League Australia YouTube channel, canvasses 'Impacting the Muslim World', with one member discussing how "when you give your money to help us reach out to these people, you are converting terrorists to know Jesus and the terrorism ends".

Another YouTube video "Julia is healed by Jesus", shows a young woman recounting her battle with depression and anxiety, which she said was healed through scripture.

"I was teaching … my pastor's kids as a swimming teacher … and she bought me to the Lord just by telling me that what was happening to me wasn't from God, and that I needed to fight," she says in the Bible League Australia video.

"It was basically spiritual warfare. This is what's happening to you. It's not from God and you need to fight. And I did that with the name of Jesus and he healed me completely.

"I was completely free after about a week-and-a-half."

Bible League also lists freeing a woman from "being demon-possessed" through gospel.

Senator Abetz stood by the group's work, but did not address whether he shared their beliefs.

"The Bible League is committed to the spread of the Gospel to all people," he said.

"The video and cameos to which you refer are the personal stories and accounts of people who accepted the Christian faith and provide a personal account of how their lives have been changed for the better."

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