ACL Chief of Staff Lyle Shelton praised the Prime Minister for highlighting marriage's cultural value.
"If politicians used the law to change the definition of marriage, that would have big cultural implications," Mr Shelton said.
"A law change would mean political correctness would dictate a new way of thinking and talking about marriage and the idea that some children can be deliberately deprived of a mother or a father would be entrenched in our culture.
"A change in the culture of marriage would also lead to increased pressure to force the church to grant 'marriage equality' for homosexual weddings as has recently occurred with the State Lutheran church in Denmark, 23 years after same-sex civil unions were granted there," Mr Shelton said.
And despite vigorous attempts by the gay marriage activists to suppress the views of the 'poly community', Greens members and even a senior party official, Simon Copland, continue to push for equality for polyamorous and polygamist people.
"Even the public debate about gay marriage has led to speculation about what cultural change is next, including by former High Court Judge Michael Kirby at the recent Senate inquiry."
Mr Shelton said former Victorian Premier Steve Bracks' observations today that Labor had lost touch with mainstream voters was especially true when it came to homosexual marriage.
"Gay marriage has been one of the highest profile political issues of the year and yet despite the party changing its policy to accommodate it, voters remained unimpressed - something a large majority of MPs know from electorate feedback."
Mr Shelton noted the Prime Minister's comment today that a vote in the Parliament would be held before the end of the year.
"As Labor MPs have said, this issue is damaging the party's brand and it is important that the issue is dealt with as soon as possible when Parliament resumes so MPs can start reconnecting with mainstream voters.
"The Opposition Leader Tony Abbott and the Coalition have opened up an area of clear advantage over Labor with Christian voters because they are sticking to their election promise to protect the Marriage Act."
Mr Shelton said ACL held its own webcast last month highlighting the cultural importance of marriage with 25,000 people in 500 churches watching the live stream.
You can view the Google+ Hangout webcast below: