New Zealand is one of only three countries in the world where the non-religious are expected to outnumber the religious by 2050, according to new research.
New Zealand will join France and the Netherlands as having the religiously unaffiliated - referring to atheists, agnostics and those who do not identify with a religion - as the majority group in 35 years.
In contrast, most other countries in the world will see an increase in Christianity and a sharp rise in Muslim populations.
Islam is the world's fastest growing religion, according to the Pew Research Centre, with Muslims expected to make up 30 per cent of the world's population by 2050 - near parity with Christians, at 31 per cent of the global population - for the first time in history.
New Zealand is one of eight countries where the Christian majority is expected to drop below 50 per cent of the population - alongside Australia, Benin, Bosnia-Herzegovina, France, the Netherlands, the Republic of Macedonia and the United Kingdom.