Census figures outlining the religious composition and sense of national identity of people in Northern Ireland will be published later.
Long-term demographic trends suggest that the 2021 Census may be the first in the region’s history to record more Catholics than Protestants in the population.
The 2011 census recorded 48% of the population as either Protestant or raised Protestant, down five percentage points from 2001. The Catholic population was 45% in the last census, up one percentage point from 2001.
The publication of the census traditionally leads to debate about what the figures might mean for the constitutional future of Northern Ireland.
Some might try to draw a direct link between the religious breakdown and public opinion about the potential reunification of Ireland.
Critics of that approach, however, see religious affiliation as a rough metric for gauging sentiment on the constitutional issue, insisting that just because someone is Protestant or Catholic does not necessarily mean their respective political views are Unionist or Nationalist.
In this connection, more emphasis can be placed on the census figures on national identity.
That question was included in the census for the first time in 2011, when 40% said they had a single British national identity, 25% said they had a single Irish identity and 21% saw their identity as Northern Irish only.
Under the terms of the 1998 Good Friday Agreement, the constitutional status of Northern Ireland can only be changed with the consent of the population.
The sitting Northern Ireland Secretary is obliged to call a referendum on Irish unity if he or she believes that there has been a change in public opinion that would indicate a majority in favor of constitutional change.
However, the 1998 peace agreement did not provide any details on what calculations or criteria should be relied upon to make this judgement.
The figures on religion and national identity are part of the second round of data to be published from Census 2021.
The first tranche of figures, published in May, related to population and household numbers.
It showed that Northern Ireland’s population had risen to a record high of over 1.9 million.
The second release of figures will also include data on ethnicity, passports held, languages spoken and a range of other demographic statistics.
Census 2021 was carried out on 21 March 2021.