In a new analysis of Pew Research Center surveys, young people are found to be less likely than those aged 40 and older to say “religion is very important” in their lives in 46 out of the 106 countries and territories surveyed over the past decade.

This is true across different economic and social contexts, in both developed and developing countries, Muslim-majority nations and predominantly Christian states, and even in societies generally regarded as highly religious.

In countries where a difference does exist, young people are less religious than their older compatriots in all but two countries.

For example, there is less likelihood of under-40s saying religion is “very important” than the over-40s not only in wealthy, secular countries such as Canada, Japan and Switzerland but also in less affluent and more religious countries, such as Iran, Poland and Nigeria.

Although the pattern is widespread, it is not universal. In many countries, Pew Research finds no significant difference in levels of religious observance between younger and older adults. On the question of religion being important, for example, no significant differences between younger and older adults are recorded in 58 countries. Yet in countries where a difference does exist, young people are less religious than their older compatriots in all but two countries – the former Soviet republic of Georgia and the West African country of Ghana.

In only two of these countries (Chad and Ghana) are younger adults more religious than their seniors.

Similarly, Pew found young people less likely than over-40s to engage in three other standard measures of religious identification and commitment: affiliation with a religious group, daily prayer and weekly worship attendance.

In 43 countries, there is a statistically significant difference between the two age groups in being affiliated with a religious group. Yet it in only two of these countries (Chad and Ghana) are younger adults more religious than their seniors.

Similarly, younger adults are more likely to say they pray daily than their elders in only two countries – Chad and Liberia – out of the 71 countries and territories for which survey data is available.

Only in Armenia, Liberia and Rwanda are under-40s more likely to attend weekly religious services, while in more than of the surveyed countries, the opposite is true.

However, Pew’s report explains that while the gaps between old and young are relatively small in many countries, a substantial number of countries show much bigger differences.

“There are gulfs of at least ten percentage points between the shares of older and younger adults who identify with a religious group in more than two dozen countries – mostly with predominantly Christian populations in Europe and the Americas,” it says.

“For example, the share of US adults under age 40 who identify with a religious group is 17 percentage points lower than the share of older adults who are religiously affiliated. The gap is even larger in neighbouring Canada (28 points). And there are double-digit age gaps in affiliation in countries as far flung as South Korea (24 points), Uruguay (18 points) and Finland (17 points).”

The most religious areas of the world are experiencing the fastest population growth.

The full report summarises a range of reasons scholars have suggested to explain why young people tend to be less religious than over-40s, including the propensity for people to become more religious as they age, and that new generations become less religious in tandem with economic development and education levels.

However, Pew researchers say, “it is not necessarily the case that the world’s population, overall, is becoming less religious. On the contrary, the most religious areas of the world are experiencing the fastest population growth because they have high fertility rates and relatively young populations.”

The study, produced with funding from The Pew Charitable Trusts and the John Templeton Foundation, is part of the Pew-Templeton Global Religious Futures project – “a broader effort to understand religious change, including the demographic patterns shaping religion around the world. Previous reports have focused on gender and religion, religion and education and population growth projections for major world religions.”