The Catholic church have angered same-sex marriage campaigners by distributing a booklet warning students that same-sex “friendships” are very different from “real marriages” to schools across Australia.

A letter, titled Don’t Mess With Marriage, was published online last month by the Australian Catholic Bishops Conference but has since been distributed directly to 56 Catholic primary and secondary schools, reports The Guardian.

The 18-page pamphlet distributed to schools lays out a tired, oft-repeated argument that “real marriage” involves “a substantial bodily and spiritual union of a man and a woman” wholly geared towards “the generation and wellbeing of children”.

“This is true even where one or both spouses are infertile: they still engage in exactly the same sort of marital acts as fertile couples, i.e. that naturally result in a child,” says the letter, magnanimously.

“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.”

“We all know and love people with same-sex attraction. They are our brothers and sisters, sons and daughters, friends and neighbours. They need love and support like anyone else,” continues the booklet.

“But pretending that their relationships are ‘marriages’ is not fair or just to them. As Christians we must be willing to present the truth about marriage, family and sexuality and to do so charitably and lovingly.”

Australian Marriage Equality national director Rodney Croome criticised the Church hierarchy’s ignorance to the negative impact the pamphlet could have on young LGBT students.

“I’m talking about young same-sex attracted people, for whom life is already hard enough, and also the children of same-sex couples,” he told News.com.au.

“But given this material has already gone out it’s only fair marriage equality advocates are invited in to Catholic schools to give their side of the issue. After all, education is about hearing and understanding both sides of an argument, not just being fed one line.”

A Change.org petition to “remove the ignorant and anti-gay propaganda” launched by one outraged Australian student, can be found here.