The latest Census 2021 results show that people in Northern Ireland have a "multiplicity of identities", experts have said.
An academic from Queen's University Belfast said the statistics show a "fluidity and hybridity" in the population which is "more diverse" than ever before.
People from a Catholic background outnumber those from a Protestant upbringing for the first time since Northern Ireland was created a century ago, the Census shows.
Read more: NI Census results: Catholics outnumber Protestants for the first time
But there are also more people identifying as having no religion, rising from 17% in 2011 to 19% - almost a fifth of the population.
On identity, 42.8% considered themselves as British either solely or along with other national identities, while 33.3% were Irish either solely or with other identities, and 31.5% were Northern Irish.
Reacting to the census figures, Dr Ian Shuttleworth told Belfast Live: "If I had to describe it in two words - fluidity and hybridity.
"Northern Ireland is more diverse. There are more people in Northern Ireland born outside the UK and Ireland than ever before.
"What you see now is a growing secularisation. And what you also see too is a growth of people who have more than one national identity, so people who have got different identities.
"It's diverse and it's fluid, and it shows the population is changing in an interesting way."
Dr Shuttleworth, of the School of Natural and Built Environment, said the figures on religious background are a continuation of trends seen in previous surveys.
"It's partly to do with population structure. The Catholic population tends to be younger. Whereas the Protestant population is older, it will have more deaths," he said.
Dr Peter McLoughlin, of the university's School of History, Anthropology, Philosophy and Politics, urged caution with interpreting what the figures could mean on the prospect of a border poll on a united Ireland.
"It's interesting that it shows there's change, but there's increasing complexity. People express a multiplicity of identities. Young people generally tend to be more pluralistic in their identity," he said.
He pointed to how those with a British identity may support the Ireland rugby team during the Six Nations championship, while those with an Irish identity may support British Premier League football teams.
"It is very complex is what I'm saying, and I would be very careful from drawing simple implications from the data."
The Census also showed a 63.5% increase in the number of people in Northern Ireland who hold an Irish passport, rising from 375,800 in 2011 to 614,300 in 2021.
Dr McLoughlin said there can be "huge practical reasons" why more people may wish to have an Irish passport since Brexit, with people seeking to retain EU rights lost when the UK left the bloc.
"I know that even Ian Paisley Jnr has been very heartily recommending that people get this, so that they don't have to queue in a longer line or whatever, so that shows the complexity," he said.
The academic said "Brexit is changing the game" and has led to "serious debate" around Northern Ireland's constitutional future.
He added: "We can't predict and overread data. But who predicted Brexit, and we don't know how it's going to pan out.
"Right now we don't have a government partly because of Brexit so it's gridlocking our institutions."
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