The Presbyterian Church in Ireland believes changes to the Constitution should be aimed at strengthening the legal status of heterosexual unions rather than promoting gay marriages.
Addressing an Oireachtas committee yesterday, Presbyterian ministers supported a call by the Catholic hierarchy for legislative options to be exhausted before any change in the Constitution.
The Rev David Moore, southern convenor for the Presbyterian Church and Society Committee, said: "If the Constitution needs to be changed in this area it should be to make explicit that the family it speaks of is that based on marriage, understood as a freely-entered-into, public and legally binding commitment between a man and a woman."
A lobby group for gay Catholics told the committee, however, that legalising gay marriage was not only "the best thing for Irish society" but "the most Christian thing to do".
The Gay Catholic Caucus, which was represented by a delegation containing two ex-priests, said: "Were Jesus alive today we believe he would open his table to gay people, along with the other marginalised groups, just as he did in his own day."
Seven other groups made submissions yesterday to the Joint Oireachtas Committee on the Constitution, which plans to produce a report for the Taoiseach by September on how best to amend the law on family rights.
Thomas Giblin, a former priest who was speaking on behalf of the Gay Catholic Caucus, criticised church teaching on the matter.
The logic of the Congregation for the Doctrine of the Faith, which had been headed until recently by Cardinal Joseph Ratzinger, was "You should not come out as a gay person because you are liable to then spread . . . the gay lifestyle".
However, he said, he hoped Pope Benedict XVI would be more Christian in his outlook and agree to meet gay Catholics.
Mr Giblin said that, by legalising gay marriage, Ireland would allow him and his partner to have their promise to each other recognised in public. It would also dismantle a "macro-closet" around homosexuality.
People like him who wanted to marry were not very visible in the gay community. "We are certainly not the majority", he added, noting that one of the reasons for this was that gay people were mostly only able to meet in dance-club type situations that were not always conducive to long-term relationships.
Dave Donnellan, also a former priest, welcomed the chance to address the committee, saying similar opportunities to air their views were very rare in the church.
The Rev Alastair Dunlop admitted that the record of the Presbyterian Church in Ireland had not been very good in the past in terms of welcoming people of different sexual denominations.
However, he said, it was working locally to be more inclusive. Nonetheless, the church would want to "hold the line" that marriage between man and woman was the norm.
He said the Constitution could not cater for all types of families. "That is where legislation takes its proper course," he added.
"Is the Constitution going to be amended every time a new situation or a new variation comes along?" he asked.
Also addressing the committee was a delegation from the Christian group, Brethren, which described gay marriage as "unnatural, immoral and evil".
