ATHEISTS in Ireland have more than doubled in number over the past 10 years, while the percentage of traditional Roman Catholics among the population is on the decline, according to the 2002 census published today.
Those who say they have no religion have more than doubled from 66,000 in 1991 to 138,000 in 2002, said the figures from the Central Statistics Office (CSO).
Almost half of those without a religion were aged between 20 and 39 and of those, 60 per cent were male.
The number who said they were Roman Catholic increased by over seven per cent to almost 3.5 million.
However, because of an 11 per cent increase in Ireland's population, the share of Roman Catholics actually fell from almost 92 per cent in 1991 to over 88 per cent in 2002.
The religions showing the biggest increase were the Muslim and the Orthodox faiths.
The number of Muslims more than quadrupled to 19,000 in the ten years and Orthodox adherents soared from just 400 in 1991 to over 10,000.
The jump in the size of both faiths follows substantial immigration during the country's so-called Celtic Tiger economic boom years of the late 1990s.
About 70 per cent of Muslims are non-Irish and over 85 per cent of Orthodox followers are also immigrants.
The CSO also reported that marital breakdown in the country was highest for those with no stated religion.
About 20 per cent of those with no religion were either separated or divorced compared to the national average of over eight per cent for all religions.