SYDNEY, AUSTRALIA - DECEMBER 16: Archbishop of Sydney, Most Reverend Anthony Fisher celebrates a mass to pay respect to the victims of the Martin Place siege on December 16, 2014 in Sydney, Australia. Sydney siege gunman Man Haron Monis, was shot dead by police in the early hours of Tuesday morning after taking hostages at the Lindt Chocolat Cafe in Martin Place. Two other people died, 33-year-old cafe manager Tori Johnson and 38-year-old Sydney barrister Katrina Dawson. Six people have been injured and have been taken to hospital. (Photo by Daniel Munoz/Getty Images)

Catholic Archbishops in Australia are leading the charge against equal marriage, ahead of a postal vote on the issue.

Australian PM Malcolm Turnbull is planning to hold a non-binding informal postal vote on same-sex marriage later this year, after coming under pressure to block an equal marriage bill.

Ahead of the vote a divisive campaign has already kicked into gear, and the Catholic Church in the country is leading the charge.

In the days since the vote was announced, both Archbishop of Sydney Anthony Fisher has sought to mobilise parishioners to back a ‘no’ vote, while the country’s Bishops have begun recirculating a missive opposing same-sex marriage.

There are more than 5 million Catholics in Australia, making it the country’s single largest Christian denomination.

Speaking to The Australian, Archbishop Fisher claimed that letting gay people marry would lead to religious persecution.

He insisted the change would have “consequences”, adding: “Many people believe that redefining marriage won’t affect them. Respectfully, I would say they need to take another look – it will affect every Australian.”

“In other parts of the world that have legalised same-sex marriage, those who believe in traditional marriage have been harassed or coerced into complying with the new view of marriage. It would be extremely naive to think that won’t happen here.”

He went on to make a string of incendiary claims, sugggesting that if equal marriage becomes law school children “will be subjected to [government] propaganda in favour of same-sex marriage and gender fluidity”.

A Church document titled ‘Don’t Mess With Marriage’ says: “Marriage is centred around and ordered not only to the wellbeing of the spouses but also towards the generation and wellbeing of children.

“A special kind of union between a man and a woman in marriage is precisely their difference and complementarity.

“Their physical, spiritual, psychological and sexual differences show they are meant for each other, their union makes them whole, and through their union ‘in one flesh’ they together beget children who are ‘flesh of their flesh’.

“They share the sameness of humanity but enjoy the difference of their masculinity and femininity, being husband and wife, paternity and maternity.

“Same-sex friendships are of a very different kind: to treat them as the same does a grave injustice to both kinds of friendship and ignores the particular values that real marriages serve.”

The Church made similar advances in Ireland when equal marriage was put to a public vote.

In that instance, the result was resoundingly in favour of same-sex marriage, despite the Church’s influence.