THE 2011 Census Figures are published on Tuesday revealing the margin between Protestants and Catholics is only three per cent.
According to the figures, 48 per cent of the population is Protestant, 45 per cent is Catholic and five per cent no denomination.
At the last Census a decade ago, the Protestant population was 53 per cent.
On the question of nationality, 48 per cent said they were British, 29 per cent Northern Irish and 28 per cent classed themselves as Irish.
However, more people in Northern Ireland carry a British passport compared to an Irish passport.
The data reveals that 59 per cent hold a British passport, 21 per cent carry an Irish passport and 19 per cent hold no passport at all.
The highest number of people who neither belong to, nor have been brought up in a religion are in North Down at 12% per cent, Carrickfergus with 10 per cent and Ards at 9.4 per cent.
One of the reasons for the decline in the Protestant population is that it is an older community with higher mortality.
Other factors include migration and the increase in the number of those who define themselves as not having any religion.
For the first time, statisticians have asked a question has been asked about national identity.
It is significant that while 45% of the population are Catholic, just 25% regard themselves as Irish only.
These figures illustrate the danger of trying to equate someone’s religion with their political identity.
The population of Northern Ireland, on the day the census was carried out in March 2001, increased by 7.5% (125,600) to 1.811m, between 2001 and 2011.
The greatest population growth rate was in the Dungannon district at 21 per cent.
The number of the usually resident population born outside Northern Ireland rose from 151,000 (9 per cent) in 2001 to 202,000 (11 per cent) in 2011.
The Local Government District with the highest proportion of people born in European Union accession countries was Dungannon (6.8%).
English was not the main language for 3.1% (54,500) of usual residents aged three years and over, almost one quarter of whom (24%) lived in Belfast Local Government District.
The most prevalent main language other than English was Polish at 1% (17,700 people).
Among usual residents aged three years and over, 11% had some ability in Irish in 2011 (compared to 10% in 2001), while 8.1% of people had some ability in Ulster-Scots.