However the new website claims marriage is defined as "one man, one woman".
The National Marriage Coalition New Zealand, Family First NZ, FamilyLife NZ, and Focus on the Family have combined to create the website.
Earlier today the site appeared to have crashed temporarily.
Visitors to the site received a pop-up internal server error message.
It said the most likely cause of the site crash was website maintenance or a programming error.
WEBSITE TO INCLUDE ONLINE PETITION
The national director of Family First, Bob McCoskrie, said it will provide "research, latest news, quotes of interest, free downloadable resources about the role and function of marriage", as well as an online petition which will presented to Parliament.
"Politicians have been hammered recently with the reasons for taking the twink bottle to the dictionary and to redefine 'marriage'. This website will help balance the debate. Ultimately, the state - which did not invent marriage - has no authority to re-invent it," Mr McCoskrie said.
He rejected the argument Kiwis are ready for same-sex marriage, saying while American polls show similar support voters there have rejected same sex-marriage when it's been on the ballot.
"Equality does not mean we must redefine marriage.
"Same-sex couples have the option of civil unions to recognise their relationship so there is no need for redefining marriage. If the law was redefined to allow same-sex marriage - and only same-sex marriage - we would then be discriminating against those seeking, for example, polygamous, polyamorous, or adult incest unions.
"If we are going to have a debate about same-sex marriage and liberalising adoption laws, it is essential that the politicians acknowledge just how far this is going to go," Mr McCoskrie said.
"Almost every culture in every time and place has had some institution that resembles what we know as marriage, and it has always been associated with procreation. Every society needs natural marriage. Nature also discriminates against same-sex couples.
"Same-sex couples cannot have children. Only a man and a woman can produce children.
"This discloses something of the purposes and providence of nature, and the role and purpose of marriage."
The campaign mirrors the Protect Marriage movement in the US, a coalition of religious and conservative groups opposing same-sex marriage in the states.