Labour MP Louisa Wall has told the Catholic Church to back off from the Australian postal survey on marriage equality until it has sorted out its child sexual abuse issues.

Wall, a Labour MP for Manurewa, was behind the same-sex marriage bill that passed in New Zealand in 2013 and says it is "disgusting" that the Catholic church would even consider speaking up about marriage equality, considering its history of child sexual abuse.

In a conversation with Buzzfeed's political podcast "Is It On?", Walls says she doesn't understand how the Catholic Church can be so involved in the Australian postal survey.

"I can't understand why they haven't been told to not lead the 'no' campaign," she said.

Advertisement

"They don't have any moral authority. How can you, when your institution over 70 years actively covered up all the sexual abuse of children?"

The church has been heavily involved in the campaign against marriage equality across the Tasman.

Earlier this week, Brisbane Archbishop Mark Coleridge compared same-sex love to "the love of friends" and said same-sex "can't be the kind of love that we call marriage".

Last month, Archbishop of Melbourne Denis Hart called upon Australian Catholics to vote "no" on the postal survey, a message also sent out by the Archbishop of Perth, Timothy Costelloe.

Wall says the church has no business trying to portray itself as a "moral crusader".

"I wish you'd talk about it and say to them, 'If you want to be a moral crusader, why don't you eliminate child sexual abuse? And be a leader in that?'" she said in the podcast. "Not against human rights, and especially in a process where young Australians are being so adversely affected.

"I find it absolutely appalling that they've come out and been so vigorous in their opposition."

She talked about the time New Zealanders successfully campaigned for marriage equality and became the first nation in the Asia Pacific region to give same-sex couples the right to legally marry.

"I believe that's where we were able to break down the generational divide. Grandparents started looking at their grandchildren and saying, 'I want for my grandchild what I want for all people. I want them to find that person and get married and have a good home and a good life and children.'"