On the other hand, homosexuality remained officially illegal in Ireland until 1993. Conservative commentators point to the speed with which same-sex marriage has become an issue with some skepticism.
David Quinn of the Iona Institute, a multidenominational religious think tank, says the Constitutional Convention was only ever going to embrace same sex marriage.
"The outcome was 100 percent predictable," he says. "The public is being very heavily conditioned to be in favor of this, and the argument [being used] is highly emotive: we love each other, why can't we get married?' "
Mr. Quinn locates the rapidity of the shift in a consensus among the political elite seeking to distance itself from Ireland's often dark Catholic history.
"Two types of country are moving to embrace gay marriage: the Scandinavian [social democracies] and ones trying to escape a Catholic past that was authoritarian: Uruguay, Argentina, Spain, and [authoritarian to a lesser extent] Ireland," he says.
The central issue for opponents is not so much the marriages themselves, but the concept of family – with children at the center of the battleground.
"Attached to genderless marriage is genderless parenting and the severing of the natural, biological tie. It's an explicit denial of this," Quinn says.
Campaigners see things differently.
Moninne Griffith of Marriage Equality says civil partnerships for gay couples, which began in Ireland in 2011, were a move forward but are not true equality.
"People in Ireland know what separate but equal means," she says, referring to anti-Catholic discrimination prior to Irish independence and in the Northern Ireland of old.