For the first time in Northern Irish history, Catholics outnumbered Protestants, a newly published census revealed.
The 2021 survey shows that 42.3% now identify as Catholic, compared to 37.3% as Protestant or of other Christian religions.
At the last census in 2011, 45% of the population identified themselves as Catholic and 48% as Protestant or of other Christian religions.
In 2001, 53% of residents declared themselves Protestant, 44% Catholic.
The turnaround in Northern Ireland – formed 101 years ago and which suffered decades of sectarian violence in the late 20th century – is likely to encourage those pushing for reunification with the Republic of Ireland.
Protestants generally argue that Northern Ireland remains a part of the United Kingdom, while Catholics generally want closer ties with their southern neighbors.
Calls to join Ireland and leave the UK fueled the violent clashes of The Troubles, which began in the late 1960s and saw around 3,500 people killed.
The conflict ended with the Good Friday Agreement of 1998, which sought to establish a balance of power between Catholics and Protestants.