Organised religion seems to be in rapid decline in Ireland, as the Catholic Church blunders from one scandal to the next and younger generations appear increasingly disinterested. Catholicism sometimes looks like a dying belief system here.
There's a catch, though, something inherent to religion which could turn the tables and devastate the nonreligious population: atheists don't tend to reproduce much.
This 2008 study in the Demographic Research journal shows that religiosity - the strength of an individual's religious beliefs regardless of denomination - directly correlates with fertility. Very religious people have more babies than less religious people.
"I find even after controlling religious denomination and demographic and socioeconomic factors, the importance of religious beliefs still exhibits a graded association with fertility in the United States.... This substantially positive effect of religious beliefs on fertility must have something to do with the role of religion in guiding human behavior in terms of the issues of sexuality, cohabitation, marriage, and the function of family."
On the face of it, this seems rather obvious, when religions like Catholicism oppose contraception use and abortion. Its consequences, though, are dramatic.
Over the last few decades many individuals raised in Catholicism have abandoned the religion, or at least taken a sceptical view of its teachings on family and sexuality. This means there are two processes at work here. One is the tendency for children of religious people to abandon or alter their religion. The other is the tendency for strictly religious people to have large families. The first force is reducing the religious population, the second is increasing it.
In Israel the high fertility of ultra-Orthodox Jews is causing their population to grow three times faster than other Israelis. By 2009 a third of Israeli kindergartners were taught in ultra-Orthodox schools, up from 26% in 2001. The population of the ultra-Orthodox West Bank settlement of Beitar Ilit grew six times faster than Tel Aviv grew in 2007 and ultra-Orthodox Jews are expected to grow from 16% of Israel's population in 2007 to 23% in 2025.
This demographic shift in Israel is happening because most Israelis don't bother with large families, but the ultra-Orthodox still do. It will be interesting to see how this affects Israeli culture and politics in the near future.
Anyway the same is true for Ireland. The media today may complacently write off the future of religion here but the future could be quite different if highly religious people continue to out-breed the rest - we may see a gradual rejection of our new liberal consensus as the conservative religious population grows once more.