The move has bought widespread condemnation from religious leaders and the Australian Christian Lobby.
Jim Wallace from the Australian Christian Lobby released a statement following the Labor Party decision saying they had chosen to be on the wrong side of truth.
"It is the wrong side of truth where gay activism has made a lie of children's birth certificates by directing that fathers' names be removed in favour of two lesbians' names.
"The wrong side of truth where gay activism has made a lie of biology so even a single man can "get" a child, as if there are no natural rights of the child to a mother.
"The wrong side of truth that allows gay activism, in the form of Elton John, to announce that he and his partner will never allow "their" baby to know its mother.
"The wrong side of truth where gay activism causes the life style to be presented as normal and healthy in our schools, when by their own data it shortens a male's life by double the years that smoking does, which we strongly discourage.
"The wrong side of truth that allows gay activism to proffer protections for the church against conducting ceremonies, while it concurrently conducts litigious attacks on the freedom of faith and conscience of the church and individual Christians wherever same-sex marriage has been granted around the world.
"It's the wrong side of truth where gay activism causes a major party to break another unequivocal election promise given by its leader before the last election that: "The Marriage Act will remain unchanged, so marriage will be defined as it is in our Marriage Act as between a man and a woman."
The ALP's decision came just hours after riot police were called in to break up scuffles between gay activists and Christian supporters of traditional marriage.
Peter Madden, who organised the rally on behalf of the Australian Marriage Forum, said he had contacted the gay-rights seeking a commitment that neither party would disturb the other's rally.
The decision of the gay-rights movement to move in on the rally marred an otherwise peaceful gathering, who heard from church leaders from a wide-range of denominations.
John Miller the parliamentary liaison for the Australian Christian Values Institute (ACVI) said, "After this weekend's Labor Conference decision on homosexual marriage, it's clear where the ALP stands on Christian values. No value and no sacrament are now safe from Labor's trendy progressives while homosexual marriage policy is in the platform."
"Working families who respect Christian values, and whose members were once the backbone of Labor and its conferences, are now considered out of date reactionaries," he added.