A study using census data from New Zealand and eight other countries suggests religion is set for extinction in all these nations, researchers say.
The data reflected a steady rise in the proportion of the population claiming no religious affiliation.
Academics from Northwestern University, in Illinois, Arizona University and a research company in Tuscon used a mathematical model to account for the interplay between the number of religious respondents and the social motives behind being one.
The American research used "nonlinear dynamics" put a numerical basis behind the decline of religion as seen in census data from New Zealand, Australia, Austria, Canada, the Czech Republic, Finland, Ireland, the Netherlands, and Switzerland.
"The result, reported at the American Physical Society meeting in Dallas, US, indicates that religion will all but die out altogether in those countries," the BBC reported today.
In New Zealand, 2006 census figures show that the number and proportion of people indicating that they had no religion continued to increase, with 1,297,104 people (34.7 per cent) stated that they had no religion, compared with 1,028,052 people (29.6 per cent) in the 2001 census.
That census showed younger New Zealanders were more likely than the rest of the population to be recorded as having no religion: 43 per cent of children under 15 years were recorded as having no religion, compared with 11.8 per cent of people aged 65 years or older.
Approximately 38 per cent of those who classed themselves as ethnically either European or New Zealander said they had no religion. Only 11 per cent of people who classed themselves as having Middle Eastern, Latin American and African ethnicity said the same.
Just over 2 million people - 55.6 per cent of those answering the religious affiliation question - said they were part of a Christian religion, compared with 60.6 per cent in the 2001 census.
"In a large number of modern secular democracies, there's been a trend that folk are identifying themselves as non-affiliated with religion; in the Netherlands the number was 40 per cent, and the highest we saw was in the Czech Republic, where the number was 60 per cent," Richard Wiener of the Research Corporation for Science Advancement, in Tucson, told the BBC.
The research pivoted on the idea that social groups that had more members are going to be more attractive to join, and that social groups had a social status or utility.
The researchers found that the relative social and utilitarian merits of membership of the "non-religious" category were similar across all the countries studied, suggesting that similar behaviour drove the mathematics in all of them.
And in all the countries, the indications were that religion was headed toward extinction.
Dr Wiener noted that it was a "suggestive result" from a fairly simple model that captured data going back as far as 100 years, and suggested the likely outcome.