The head of Australia's Anglican Church won't be advising its members how to vote in the same-sex marriage postal survey, but will himself be voting no.
Archbishop Philip Freier has written an open letter urging all Anglicans to "exercise their democratic right" and engage in the debate in a sensitive way.
"Anglicans, like other Australians, have a wide range of opinions on same-sex marriage, supporting or opposing it for a variety of reasons in accordance with their conscience and their understanding of the principles and issues," he wrote.
"I do not presume to advise others how they should vote, though I myself intend to vote no."
Although the survey was not binding the parliament would find it hard to ignore the will of a majority of Australians, Archbishop Freier said.
In the 2016 census, 3.1 million Australians, or 13.3 per cent of the population, cited an affiliation with the Anglican Church.
The church's national "parliament", the General Synod, is due to debate the issue at its meeting which starts this Sunday on Queensland's Sunshine Coast.
Dr Freier said doctrine set out in the church's Book of Common Prayer remained unchanged, that marriage is "between a man and a woman, under God, forsaking all others until death parts them".
"I do not believe that the Anglican Church in Australia is likely to revise its doctrine of marriage," he said.
"But that said, the church also understands the desire of two people to express their commitment of love and self-sacrifice to each other, and that Christians have not always shown the respect or perspective they should.
"We understand that sometimes gays, lesbians and others have felt judged and rejected, even ostracised, inside the church and that we have to be much more pastorally sensitive in future."