Barry McCrea: Oh come ye, oh come ye to Dublin

The Dublin of my childhood in the 1980s was the capital of a collapsing economy, a twilit abandoned bus-shelter at the edge of the world.

Mass emigration affected everyone then, including the middle classes. People in their twenties vanished automatically from that damp world, and would reappear at Christmas, like ghosts, before evaporating again. For a child, oblivious to the rhythms of adult time, and a stranger to the pain of prolonged physical absence, these shadowy figures were part of a purely Christmas reality, exotic attendants in the background of the celebrations, like the Three Wise Men.

We know nothing from the Gospel about the Wise Men's lives back in the "Orient", only their short role in Bethlehem: their awe at finding the miracle they had hoped for, their joy at being in the right place at the right time, and, one imagines, their giddy excitement at being there together. In the same way, Dublin's Christmas travellers, after paying quick homage to the families they had come home to see, raced out to find each other in the pubs and streets to recreate the Dublin they had lost – not only the separation from individual loved ones, but also the general sense of being surrounded by faces and bodies you have known at different stages of life, that sense of time and change you lose when you emigrate.

The boom years, which lasted from the mid-1990s to yesterday, changed everything about Ireland, in now very well-known ways: dank alleys became smooth granite thoroughfares, petrol stations became apartment blocks, no money became loads of money. When I emigrated to the US in 1997, for the first few years the Aer Lingus flights back at Christmas were mostly populated with two types: weather-beaten old couples, shy and patient, who had left in the 1950s, and still-young 1980s immigrants who would run into old friends and arrange to meet up for drinks on Christmas Eve. Somewhere around 2002, to these two groups was added another layer of "returning" Dubliners – the throngs who lived at home but came to New York to do their Christmas shopping, 10-year-old children laden with boxes from FAO Schwarz and bags from Sachs Fifth Avenue, wielding twee candy-canes and faux-Victorian teddy-bears as they pushed past into the Premier cabin (one imagined them reclining in the Premier seat and demanding a Cosmopolitan).

This new group of travellers caused confusion among the rest of the returning emigrants. The boom had changed everything, even the Dublin accent, which had gone partly global. My old Irish "t" in words like "butter", for example, sounded ill-equipped for our new fast-paced economy next to the Celtic Tiger couples bring back "compuders" from New York "Siddy". For the rest of us on the plane, eager to go "home" from America, it could feel like we had no home to go to, as though with our hissy "t"s and damp, grey memories, we had become citizens of a forgotten island, now vanished beneath the waves forever.

But this uncertain overlap of different times and different worlds was always part of Christmas in Dublin, and, in fact, still now "everyone" is there. In Matthew's Gospel we learn the place of Jesus's birth only in the context of the Magi's journey – the pilgrims partially make the destination. Boom or no boom, Irish people still have a tendency to move abroad, and to come back for Christmas; and, since Ireland and Dublin are so intimate and centralised, going into town for the shopping rush means to be confronted with a parade of schoolfriends, former neighbours, cousins, enemies and old flames all reappearing, older, fatter, greyer, kinder. "Everyone" is there, those who live abroad, those you have not seen in years, those you love and those you try to avoid. As the season pushes on, and the planes from New York and London and Frankfurt keep pouring into the city ever more characters no longer part of its daily life, it is no longer clear to those who live in Dublin who is back from abroad and who "really" lives there too, but who have been out of sight or mind. Since any of the forgotten faces might be emerging either from foreign places or from the past, the dead may as well be there too, mingling with the harried crowds on Grafton Street.

Joyce's Christmas story in Dubliners is called "The Dead". "Snow was general all over Ireland," its last paragraph tells us, "faintly falling... upon all the living and the dead". Indifferent to happiness or sorrow, finding expression in consumerism or Catholicism or in neither, Christmas in Dublin is "general", covering all of us, and collapsing all times into one. Those who return from abroad bring with them the Dublin of the past which, for good or for ill, they carry with them in their hearts; newer Dublins appear in the changed faces and streets they encounter. This one time is all times, happy or unhappy; home is abroad and abroad is home.

In late December, Dublin is dark, each day a long night broken only by a few midday hours of viscous, longshadowed light. It is like the span of an individual life, a momentary, pale interruption in a blackness stretching out into infinity on either side. The emigrants who come home leave behind the streets and accents and labour of their day-to-day lives, and for the city as a whole, as December pushes inexorably onwards and Christmas approaches, it gradually effaces the ins and outs of regular daily life, like Joyce's snow, slowly but unstoppably covering everything. The rest of the world recedes, global connections fall away; Dublin is suddenly linked not to other places but only to other times, and thus becomes the only place that feels fully real.

The anthem of this annual, timeless world is "Adeste Fideles", an exhortation to the faithful to all gather together in a miraculous place. The "faith" in the song is nominally a Christian one, but Christmas was there long before Christianity, and it flourishes still in post-Catholic Ireland. The true faith is in the endurance of this recurring moment outside the ordinary progress of our individual days. For this the faithful find themselves called back to Dublin every year, bust or boom or bust again: for the festival of light in the blackest depths of the year, to step outside the march of time and keep each other company against the looming darkness beyond.

Barry McCrea's debut novel 'The First Verse' is published by Brandon