The sponsor of a bill to legalise same-sex weddings says marriage is an evolving institution and many opponents of a law change were in denial about the fact that homosexuals had held equal rights in New Zealand for 27 years.
The debate on gay and transgender marriage resumed yesterday as Labour MP Louisa Wall was the first person to make submissions on her own bill.
She said gay rights was a generational issue, and denying homosexuals the right to marriage would be out of step with the youth of the country, who overwhelmingly supported it.
The University of Otago and the University of Victoria had held referendums on same-sex marriage and found 84 per cent of students in support.
"I think for younger New Zealanders, the issue of marriage equality is one where they can't see what the problem is," Ms Wall said.
"For them, it is about principles of equality and non-discrimination. They haven't got the hang-ups of homosexual law reform that I believe some older members of New Zealand have."
She said some opponents were being dishonest in opposing the bill when what they truly opposed was homosexual law reform.
Her decision to draft the marriage equality bill was strongly influenced by the international shift towards gay marriage, in particular President Barack Obama's vote of support.
Yesterday, two more American states approved measures to legalise same-sex marriage.
Ms Wall previously said marriage was a basic human right, and that a law change would ensure that the state did not discriminate.
She was challenged in the select committee by National MP Kanwaljit Singh Bakshi, who voted against the bill at the first reading.
"I respect human rights for everyone, but marriage is between a man and a woman," he said. "Can't we fix it another way?"
Ms Wall said alternative policy changes such as making adoption law fairer did not eliminate the inherent discrimination in marriage law.
Much of her submission debunked arguments. Churches would not be forced to marry gay couples, she said, and pastors would not be prevented from criticising same-sex marriage from the pulpit.
The MP dismissed as insulting the argument that passing same-sex marriage was a "slippery slope" to polygamy, bigamy, bestiality and incest, which remained criminal offences. The bill passed its first reading by 80 votes to 40, which meant it was likely to pass into law.