The debate on same-sex marriage has stepped up with both ends of the Church spectrum weighing in and a former MP comparing the proposed law change to "apartheid".
A select committee has begun the task of hearing a selection of more than 20,000 submissions on a bill to legalise gay and transgender marriage.
Committee member and Green MP Kevin Hague said the submissions yesterday ranged from "great" to "confused".
Former Dean of the Holy Trinity Cathedral Bishop Richard Randerson spoke in support of the bill on the grounds that marriage was a committed union which provided a stable environment for children.
The Anglican leader said this was not only a religious ideal but was backed by social science.
Bishop Randerson argued that the Bible was not clear-cut in its condemnation of homosexuality.
"The question of long-term, committed, same-sex relationships was just not an issue that was considered in biblical times.
"What we look for in the Bible are ongoing, unchanging principles, and those principles, I believe, are committed care, even at some cost for another person."
Family Life International NZ co-ordinator Clare McLean said same-sex marriage was not about human rights or fairness but about changing the definition of marriage. She argued that marriage was not defined by law or the Church, but by nature and biology. Marriage was designed for the "ultimate end", which was creating and raising children.
"Marriage is more than a loving relationship, it's a one-flesh complementary union bringing about the procreation of children."
Asked by an MP whether this argument meant infertile couples had a different status and should not be able to marry, Mrs McLean said: "Not at all. It's not of their choice that that has happened, it's part of nature."
The submission process was mostly a respectful affair, but chair Ruth Dyson had to warn some submitters that their comments could be deemed insulting.
Former United Future MP Gordon Copeland upset some of the committee when he said same-sex marriage reminded him of apartheid.
He said the premise of gay marriage was comparable to apartheid South Africa inviting Maori rugby players to the country as "honorary whites".
Mr Copeland, who ran as a Conservative candidate in last year's general election, described marriage as New Zealand's most precious institution.
United Future leader Peter Dunne distanced himself from his former colleague, calling Mr Copeland a "serial nutter". He added that the Conservative Party was "welcome to him".
Green Party MP Kevin Hague challenged a Catholic group which had argued that biological parents gave their children a better upbringing.
"Can you explain to me how my getting married to my same-sex partner actually threatens children in any way?"
A spokeswoman for Catholic Women's League of New Zealand responded: "Mothers and fathers are very different in so many ways that it's the combination is ideal for children. The balance of male and female is the best of all."
King's Church Wellington spokesman Lawrence Collingbourne was concerned about how the bill could affect religious freedom. He felt there were insufficient protections in the Marriage Act for ministers.
The select committee has sought a legal opinion on whether the law change could expose religious leaders to human rights breaches.
The bill's sponsor Louisa Wall has previously said the law change would not undermine pastors' right to speak freely from the pulpit, or their right to refuse to marry gay couples.
Kiwiblog founder and National Party pollster David Farrar predicted that in less than 25 years gay marriage would be a "non-issue".
He pointed to the change in public opinion in the United States, where support for same-sex marriage had shifted from 32 per cent to 54 per cent in six years.
"It's an absolute tidal wave. I think it's reflecting that there's a younger generation who having grown up in the current era have an absolutely relaxed view on this."