For the first time, those in Northern Ireland (UK) that define themselves as Roman Catholics  outnumber those who identify as Protestants.

This is what the latest general census data published this September by the Northern Ireland Statistics and Research Agency (NISRA) for the year 2021.

According to the document, up to 45.7% of the Northern Irish population identify with the Catholic creed, while 43.5% identify with one of the branches of Protestantism (including evangelical Christians). These figures show a clear reversal from 20 years ago, especially in the Protestant sphere, when 53% of the population considered themselves Protestant.

In the case of Catholics, the numbers do not vary much: in 2001 they were 44% of Northern Ireland’s demography, according to NISRA, only one point below what they register now.

The census also shows that 9.3% identify with other religions, and about 20% to none in particular.

The census results have added to the debate in Northern Ireland over whether to hold a referendum to reunify the island since Brexit took effect. They also coincide with the victory of the Irish republican Sinn Féin party in the last regional elections.

Why ask about religion?

The Northern Ireland Statistics and Research Agency has also published a document explaining why questions about religion are included in its national census, saying knowing the faith of the population is needed to “help plan public services”. The inclusion of questions of religion has received “continued public support”, they add.

NISRA has received more than 1.8 million responses to its survey. Of these, only 1.5% of respondents did not complete the section on religious identity.

In total, the institution says that the recorded response rate to its surveys has reached 97%, five points higher than in 2011.