A Catholic priest this morning has said he is "saddened and concerned" with last night's vote to legalise same-sex marriage.
Father Merv Duffy, speaking on Firstline this morning, described the new law as "bizarre", comparing it to a 19th century attempt to legislate the value of a mathematical constant.
"In 1897 the Indiana state legislature attempted to pass a bill which among other things would have made pi equal to 3.2 – which is mathematically wrong," says Father Duffy, who believes marriage is a "pre-existing reality" that cannot be changed through legislation.
"Fortunately they were stopped before they passed the bill, but even if they had passed the bill, the reality would not have changed."
Labour MP Louisa Wall's Marriage (Definition of Marriage) Amendment Bill passed into law 77 votes to 44, a margin identical to that in its second reading. This morning Ms Wall dismissed feedback from religious opponents, saying their submissions weren't based on evidence.
Father Duffy says that's because it could take 50 years to see the negative effects of legalising same-sex marriage.
"Change can be beneficial, or have negative consequences," he says. "This could have negative consequences, and they're going to be subtle, and it could take 50 years before we actually see what results from this. The one I fear most is a weakening of respect for the marriage bond itself."
He says marriage is already under threat from changing attitudes towards sex and dating, let alone gay marriage.
"The interesting thing is marriage is under a lot of threat, largely from cohabitation, where there are many heterosexuals who don't want to marry… Not everything that's happening in necessarily good."
In his view, love has nothing to do with the Biblical idea that marriage can only be between a man and a woman.
"We're not talking about love – we're talking about marriage… there are many marriages which are not love matches," he says, adding that society has "honoured and prioritised one" form of love above all others – that between husband and wife.
"I think our Parliament has made a change to the social fabric of New Zealand society. They've redefined a very core relationship.
"It has been as it is for a very, very long time, and this is a classic sort of liberal vs conservative thing. Liberals think you can legislate to make the world a better place – conservatives worry, what happens when you change things?"
Churches and celebrants will not be compelled to host or officiate same-sex marriages, under section 29 of the bill.