Anglican Archbishop of Sydney Glenn Davies has told Anglican supporters of same-sex marriage they should leave the church rather than “betray God’s word” in a scathing speech condemning progressive elements within the faith.

He said the church must focus on “evangelising Australia” rather than “the constant pressure to change our doctrine in order to satisfy the lusts and pleasures of the world”.

Dr Davies directed his strongest criticism at church branches that had moved to bless same-sex unions, such as the Wangaratta diocese in Victoria. That decision has now been referred to the church’s internal appeals tribunal.

Anglican Archbishop of Sydney Glenn Davies said supporters of same-sex marriage should leave the church.

Addressing the 51st Synod of the Diocese of Sydney, the Anglican church’s parliament, on Monday, Dr Davies warned the church had “entered treacherous waters” and called on those who supported same-sex marriage to leave.

“I fear for the stability of the Anglican Church of Australia. These developments have the potential to fracture our fellowship and impair our communion. I have stated this on numerous occasions at the annual National Bishops’ Conference, but sadly to little effect,” said Dr Davies, who is the Synod president.

“My own view is that if people wish to change the doctrine of our church, they should start a new church or join a church more aligned to their views – but do not ruin the Anglican Church by abandoning the plain teaching of Scripture. Please leave us.

“We have far too much work to do in evangelising Australia to be distracted by the constant pressure to change our doctrine in order to satisfy the lusts and pleasures of the world.”

Dr Davies said to bless same-sex unions would be to “betray God’s word”. He conceded “our view of marriage is not a popular one in Australia” and was also now contrary to the law.

“Nonetheless, God’s intention for marriage has not changed. We honour him when we abide by his instruction. We cannot bless same-sex marriages for the simple reason that we cannot bless sin,” Dr Davies said.

The church’s General Synod will meet next year in Maroochydore for a special session on the question of same-sex unions. Dr Davies said it was imperative decisions were made given the acts of rebellion in some church branches, and the conference “must make a clear statement about the teaching of the Bible on the sanctity of sex within the marriage bond of a man and a woman, so that marriage is held in honour among all and the marriage bed is not defiled”.

During the 2017 postal survey on marriage equality, the Sydney Anglicans under Dr Davies donated $1 million to the “No” campaign.

The hard-line position of the Sydney diocese has been controversial within the national church. Dr Davies announced he would step down as archbishop in July, shortly before he turns 70.

Dr Davies also discussed gender identity, noting the church was experiencing an increase in the occurrence of gender dysphoria issues.

“A doctrinal position that expresses the doctrine, tenets, beliefs and teachings will be necessary for the protection of our religious freedom, as well as providing protection from future charges of discrimination that may well be brought against the church or its organisations and schools,” he said.

Dr Davies called on Anglicans to “pray for our politicians, especially Christians on both sides of politics” as they worked towards a final version of the Religious Discrimination Bill.