Catholicism is still the dominant religion in Ireland as 3.7m people declared themselves as Catholics in this year's Census, down 3.4 percent since 2011.
Offaly has the highest percentage of Catholics in the country at 88.6 percent, while Dun Laoghaire - Rathdown in South Dublin has the lowest percentage at 69.9 percent.
'No religion' is the second most popular religion in Ireland with 10 percent of the population (468,421) not identifying with any faith. It's an increase of 73.6 percent in five years, making it the fastest growing 'religion'.
The Church of Ireland has the third highest membership with 126,414 people, while census figures show that the Muslim (Islamic) population has risen by 28.9 percent since 2011 with 63,443 members.
Meanwhile the Christian Orthodox religion saw the second biggest growth at 37.5 percent with its numbers standing at 62,187, with Romanians making up 33.5 percent of the overall population.
Census data also looked at ethnicity in Ireland. Those who indicated a “White Irish” ethnic or cultural background amounted for 88/2 percent of the population.
This was followed by 'any other White background' at 9.5 percent, 'non-Chinese Asian' at 1.7 percent and 'other incl. mixed background' at 1.5 percent.
The vast majority (94.1 percent) of those with a 'White background' were born in Ireland. Of the 5.9 percent (226,078) born elsewhere, 121,174 were born in England and Wales and 53,915 were born in Northern Ireland.
Of those with “Any other Asian background', 22.4 percent were born in India, followed by 16.1 percent in the Philippines and 13.7 percent in Pakistan.
The figures show that the Irish Travellers' population (30,987) has risen by 5.1 percent since 2011. Dublin city and suburbs had the largest number of Irish Travellers with 5,089 persons. This was followed by Galway city and suburbs with 1,598 persons and Cork city and suburbs with 1,222.