"The sky has not fallen in. All that happens is that people who want to commit to each other are able to," he said.
Openly gay UUP councillor Jeff Dudgeon fought a long legal battle to decriminalise homosexuality here in the 1980s.
But he warned that some politicians would vote to have decriminalisation reversed if a bill allowing same-sex marriage is introduced at Stormont.
More than 60% of those who cast their votes ticked the ‘yes’ box, and the cross-party support in the south turned attention to Northern Ireland, the only part of the UK and Ireland where same sex couples cannot be legally married.
Cllr McDonough-Brown said the “sun shone” on the Republic of Ireland on 23 May, the day the referendum results were revealed.
Supporting members of the lesbian, gay, bisexual, and transgender societies, he said: “Their contribution makes our society a more vibrant one.
“I look forward to Northern Ireland joining the list of countries that allows couples to say I do.
“The sky has not fallen in. All that happens is that people who want to commit to each other are able to.”
Cllr McDonough-Brown described NI as a “backwater, an embarrassment” in its stance on gay marriage, but added that ministers should not be forced into enacting it.
“Alliance believe religious insitutions must be free to practice marriage as they see fit,” he explained.
The token motion, which would likely be defeated at the Assembly if proposed at Stormont, was seconded by Sinn Féin councillor Jim McVeigh.
Still wearing the ‘yes badge’ from the southern campaign, he said a mood of tolerance and mutual respect is infectious.
“This is the type of politics we should be talking about. There’s a groundswell of goodwill sweeping across these islands,” he said.
“I remember when fire and brimstone dominated politics here. This place is changing.”
The Lower Falls representative recalled the Save Ulster from Sodomy movement - started by Rev Ian Paisley - which Cllr McVeigh claimed was once the biggest campaign in Belfast.
“Now the second biggest rally in the city is Pride,” he added.
“Whether or not we manage to change the minds of the DUP, their position is only a matter of time.
“What an act of forward leadership to say this country belongs to everyone.”
“One of the ironies about this debate is that some of the people who opppose it say it undermines the insitution of marriage. How does love undermine marriage? I don’t understand how they feel it undermines it. In fact, it’s quite the opposite.
“It’s time for this part of this island, of these islands, to support marriage equality,” added Cllr McVeigh.
Openly gay councillor Jeff Dudgeon also spoke up during the debate. The UUP politician remembered back to 1982, when homosexuality was made legal in Northern Ireland, just over a decade before politicians in the Republic made the same change.
“There was a small party in Belfast of a dozen people, and then a disco. Not a street party with global support,” he explained.
“Most countries in Europe still don’t have equal marriage.”
He also referred to how politicians voted at Stormont during a Sinn Fein proposal in April to allow same-sex marriage in Northern Ireland.
It led to questions over divisions among the SDLP and Alliance parties on their members’ stance on the issue. Five SDLP MLAs did not turn up for the vote, while three Alliance party representatives abstained, despite official party line being to support gay marriage.
Cllr Dudgeon said: “Decriminalisaton in the 1980s was achieved without support from any political party. The Alliance party doesn’t discipline its members that don’t abide the party whip.
“This bill would still hve to go through Stormont where it’ll be defeated, and I’m nervous of those being demonised for their stance.
“In my own party there are differing views, we hold the status quo, though some have already voted for change.”
Cllr Dudgeon was a trailblazer in making homosexuality legal in Northern Ireland, taking his case to the European Court of Human Rights. Less than a decade later, David Norris also arrived at Strasbourg in a case that echoed Dudgeon’s.
The Unionist politician expressed fears that some politicians would vote to have the decriminalisation of homosexuality reversed.
“My colleagues at the High Court and at Strasbourg will once again be the agents for change.”
During the vote on Monday night, the motion was carried 38-13, with two no votes.