The Anglican bishop of North West Australia says he may refuse to marry all couples if the 'yes' vote triumphs and religious protections are not provided.
Bishop Gary Nelson has criticised the federal government for its handling of the same sex marriage postal survey, saying details of the legislation should have been released beforehand.
He expressed concern the Commonwealth had not been clear about possible religious exemptions and said the diocese might have to withdraw from registering all marriages.
Bishop Nelson said the church believed marriage was only between a man and woman.
"Same sex marriage is fundamentally opposed to what we believe," he told AAP on Thursday.
"I guess it comes down to whether you take the Bible seriously or not.
"People have wandered away from the teachings of the Bible."
Bishop Nelson, who admitted some Anglican leaders in Perth disagreed with him, denied it came down to interpretations of the Bible, saying it was "pretty clear".
The conservative bishop said each diocese was independent, so no senior Anglican could order him to change his position.
The Anglican Church of North West Australia has 18 parishes covering an area of two million square kilometres, stretching from Dongara in the south to the top of WA, and east to the South Australia/Northern Territory border.
It comes as Anglican Dean of Brisbane Peter Catt hit out at a Sydney diocese's decision to donate $1 million to the 'no' campaign.
"I would have thought that million dollars could have been spent on something that the church is more agreed on, say looking after the homeless, the plight of the refugee - the list goes on and on," he told ABC radio.
Dr Catt, who supports marriage equality, said he would have also been against money being spent on the 'yes' campaign.
"All campaigns should be equally funded by the government so people can make informed choices rather than the people with the most money getting their view up," he said.
