The Northern Ireland Assembly is to debate redefining marriage at the end of the month, despite the Assembly having twice rejected similar proposals.
Four MLAs have tabled a motion for debate, saying the Province needs to be in line with the rest of the UK.
But MLAs defeated two previous attempts to introduce same-sex marriage, once last year and once in 2012.
The private member’s motion, tabled by three Sinn Fein MLAs and one Green Party MLA, calls on the Minister of Finance and Personnel to introduce gay marriage legislation.
Speaking in reaction to the first gay marriages in England last weekend, David Smyth, public policy officer at Evangelical Alliance Northern Ireland, said: “While Saturday was a day of celebration for some, it was a concerning day for many.
“Christian opposition to same-sex marriage was never just about protecting churches. It’s always been about the wellbeing and welfare of family and communities for generations to come.
“The whole idea of ‘equal’ marriage comes from a premise that many outrightly reject, that marriage is an inequality to be corrected”, he added.
Last year, Amnesty International and a homosexual lobby group in Northern Ireland claimed a legal challenge could be made if marriage is not redefined in the Province.
Amnesty International’s programme director in Northern Ireland said international law was “clear” that different parts within a territory should provide in the same way for same-sex couples.
Patrick Corrigan said: “There could be a straightforward legal challenge on the basis of inferior treatment of same-sex couples in Northern Ireland with regards to the right to marry and found a family.”
MLAs rejected same-sex marriage last year by 53 votes to 42, and in 2012 the plans were voted down 50 to 45.
Next year the Republic of Ireland is to hold a referendum on gay marriage.
But the Roman Catholic Church said it will seek to keep the law as it is, saying: “To change the nature of marriage would be to undermine it as the fundamental building block of our society.”
And the Iona Institute, a campaign group which promotes the place of marriage and religion in society, said changing the law for same-sex couples is not an issue of equality.
Dr John Murray, one of the directors of the organisation, said: “This debate is really about the value we attach to a child having a mother and a father as distinct from two fathers or two mothers.”
The Scottish Parliament voted to introduce gay marriage in February this year.