The Anglican Diocese of Sydney has donated $1 million to fund the campaign against same-sex marriage in Australia.

The Archbishop of Sydney, Glenn Davies, confirmed on Monday his heavily conservative diocese, the largest in the country, had backed the 'no' campaign in Australia's forthcoming postal survey on gay marriage.

'The stakes are high and the cost is high,' he told a meeting of all the churches in Sydney on Monday. 'Yet the cause is just and it is a consequence of our discipleship to uphold the gift of marriage as God has designed it – a creation ordinance for all people.'

He added he would 'make no apology' for urging Australians to vote 'no' in the poll, which was commissioned by Prime Minister Malcolm Turnbull to advise parliament but is not legally binding.

'I consider the consequences of removing gender from the marriage construct will have irreparable consequences for our society, for our freedom of speech, our freedom of conscience and freedom of religion,' he told the synod. 'It is disingenuous to think otherwise.'

He added: 'We find ourselves being moved in a more libertarian direction under the influence of those who want to abandon the mores of the past.

'These permissive forces who espouse the virtue of tolerance are seeking to impose restrictions upon those who wish to maintain the values on which our nation has been founded,' he said according to The Australian.

'This has become nowhere more apparent than in the current debate surrounding the postal survey on same-sex marriage.'

Moving on to discuss abortion and assisted suicide, Dr Davies said he had written to the area's parliamentarians on behalf of all the churches to oppose any attempts at liberalisation.

But the Anglican Church of Australia is split on the issue with the newly elected first female Anglican Archbishop, Kay Goldsworthy, strongly hinting that she personally backs same-sex marriage. She said she has an 'inclusive' approach to the issue but respects the wider position of the Church.

Both sides in Australia's increasingly toxic debate over gay marriage claim to have been outspent by their opponents.

Executive director of the Equality Campaign, Tiernan Brady, said the donation was evidence that 'opponents of equality have radically outspent the Yes side'.

He told The Australian: 'But what they have in buckets of cash, we make up with in hundreds of thousands of Australians making the case for a fairer, more just and inclusive society.'

However despite repeated claims from the Yes side they were being outspent, it emerged last month Qantas chief executive Alan Joyce also personally donated $1 million to the campaign in support of same sex marriage.