The eighth amendment of the Irish constitution makes Ireland, depending on your point of view, either a unique beacon of humanity in a godless world or a superstitious hamlet determined not to enter into the 21st century. The amendment was signed into law in October 1983 after two-thirds of the electorate voted in a referendum to accord equal status to the life of a child growing in the womb with that of its mother. As a result, only in extreme circumstances can an abortion take place.

Pointing out that no one under the age of 52 had ever voted on the issue, the taoiseach, Leo Varadkar, last week announced that a referendum would take place by the end of May to repeal the amendment.

All over Ireland, old arguments are being dusted down and fortified, and red lines are appearing in the sand again. It’s not enough to say that this is a country divided; all democracies are divided – by class, geography, money. Ireland right now is experiencing convulsions. This is what happens when an old order which has held a people in its grip for centuries is forced to let go. We are witnessing the long, slow separation of the Holy Roman Catholic and Apostolic Church and the Irish state.

In the course of this generation, the constitution has been amended to remove the prohibition of divorce in 1996, and 20 years later the Irish people voted overwhelmingly to approve same-sex marriage.

Now a woman’s right to have an abortion, a right held to be sacred in about 200 other countries, is about to be accepted in what is often perceived as the world’s most Catholic country. If this isn’t recognised in May, it must only be a matter of time before it is.

In Roscommon last week there was quiet unease at the prospect of another referendum that would test the depth of the old faith and the resolve of another moral certainty. The county sits in the centre of Ireland and some of its citizens remain resentful at the buffeting it received following the referendum on same-sex marriage in 2015. Roscommon was the only one of Ireland’s 26 counties to vote against. This led to a slew of abuse and online mockery. “Go home Roscommon, you are drunk,” was one tweet. This was another: “Tip, I’ll give you a tip! Move to Roscommon/South Leitrim and pal around with your own kind of hate-filled bigots.”

Christina McHugh, editor of the Roscommon Herald, understands the hurt felt by many at being depicted as an uncivilised and backward horde. “What people failed to acknowledge,” she says “is that Roscommon has the highest concentration of elderly people in Ireland. Unemployment and lack of opportunities means many young people leave as soon as they can.

Facebook Twitter Pinterest Roscommon has the highest concentration of elderly people in Ireland. Photograph: Alamy

“The vote on same-sex marriage here was very close, around 51%-49%. Even so, it was a democratic election and people had a right to vote the way their conscience dictated without being abused.”

The paper she edits will remain neutral during the debate. “It’s not our job to tell readers how they should be voting on this issue,” she says.

It was evident, too, that some of the undercurrents that fuelled Brexit and Donald Trump’s storming of the White House were present in Roscommon. This is a rural county which has always done things its own way and is accustomed to delivering surprising election results. There is a sense of seeking to tell Dublin’s sophisticated political set that another Ireland exists and that it won’t simply roll over to indulge the sanctimonious whims of a rootless city mob.

Varadkar has said he hopes the abortion referendum will be conducted in a civilised and mutually respectful manner, but this seems optimistic. The battle over the eighth amendment will pulse with more emotion than the same-sex marriage struggle.

Eugene Murphy, who represents Roscommon-Galway for the opposition Fianna Fáil, meets me in his office at the top of the town’s main street. He will be voting against the amendment but he speaks with compassion: “I have made my position clear on this issue. But I fully respect the views of those who disagree with me. Of course it’s a very emotive issue and people have strong views because it concerns the health of mothers and the lives of unborn children.

“There is no easy answer and I think many people on the No side would concede that there may be circumstances when abortion is advisable, but I think the Taoiseach has made a mistake in opening it up to an ‘on-demand’ level. It’s this which I think will see it voted down by people who otherwise might agree to abortions where there has been rape or incest or where there is a genuine threat to the life of the mother.”

Murphy’s media adviser and office organiser Mairead O’Shea has a different view. “I will probably vote to amend,” she says, “as I just don’t think the state should be interfering in what is such a deeply personal and painful issue for women. I happen to think there are many people who are pro-life themselves but who are reluctant to force their views on to another who doesn’t hold those beliefs. We have seen an upsurge, too, in the number of young people seeking to register to vote.”

The problem for those who are basically anti-abortion but would permit it in cases of rape or incest is that it is well-nigh impossible to legislate for such a narrow corridor of wickedness. The issue of how rape victims are dealt with and how many of these cases actually make it to court is already a tender one, without adding the fate of an unborn child into the mix.

Facebook Twitter Pinterest Leo Varadkar hopes the referendum will be fought in a civilised manner. Photograph: Niall Carson/PA

The battle for the eighth has already seen one politician tie himself in knots. Varadkar’s deputy, Simon Coveney, has sown confusion in his party and in the country by insisting that the state has a duty to protect unborn children, despite also stating that he will vote to repeal the amendment.

Early indications are that the result will be far closer than the 62%-38% in favour of same-sex marriage. Varadkar has moved to ban all outside funding in the campaign, but this won’t stop hundreds of overseas activists on either side descending on Ireland in the days leading up to the vote. This is when it will become intense and when rancour will enter the debate.

Outside the Roscommon branch of Dunne’s Stores on Friday afternoon, I conducted my own mini-referendum. Of the eight women of varying ages who agreed to speak to me, not one intended to vote against repealing the amendment. Bridie Connolly eloquently encapsulated a prevailing sentiment among these women. “In cases of rape and incest, and if there’s a diagnosis of foetal abnormality, then it should be left to the mum and dad to decide. Ireland’s healthcare system is a mess and ill-equipped to care for sick children as it is.”

In devout, rural Ireland, the foundations are already beginning to shift beneath a church whose authority has for long been a fragile thing.