Religious organisations are losing their teenagers, according to a new report. Teens and young adults from the Millennial generation are not only less religious than previous generations, they are less spiritual as well, the study warns. The exceptions are the black communities and political conservatives.

The report challenges the received wisdom that Millennials, who followed Generation X, remain interested in a spiritual dimension even when they have rejected organised religion.

They are instead more likely to be part of the emerging "nones" group, identifying with others who write "none" on surveys and forms when asked to state their religion.

The study shows that Millennials have less approval of religious organisations than previous generations, are less likely to say that religion is important in their lives, are less spiritual and spend less time praying or meditating.

Collating data on 11 million adolescents from several national surveys covering 1966 to 2014, Jean Twenge, of San Diego State University, and others write in an academic article for the 'Plos One' journal that a decline in religious orientation suggests a move toward secularism by a growing minority.

The decline is largest among girls, whites and in the Northeastern United States. It is far smaller among black Americans and non-existent among political conservatives. There is also less religion among families with higher incomes, among people who have more positive views of themselves and among people who need low levels of social support.

"American adolescents in the 2010s are significantly less religiously oriented, on average, than their Boomer and Generation X predecessors were at the same age," write Twenge and her colleagues. "Unlike previous studies, ours is able to show that Millennials' lower religious involvement is due to cultural change, not to Millennials being young and unsettled."

Importantly, they continue, the declines also extend to the importance of religion, spirituality, and prayer. They say these effects are both smaller and more limited are not consistent with the idea that young Americans are less religious but not less spiritual.

American adolescents are now less likely to attend religious services. Compared to the early 1970s, more than twice as many college students in the 2010s never attended services, according to Twenge.

The study says the religious orientation of adolescents is important because religiosity is associated with a wide range of positive factors including fewer risk behaviours, better social functioning, less substance abuse and better physical health. Compared to other adolescents, religious adolescents also report less depression, anxiety, and other psychiatric concerns and display character strengths such as fidelity to their partners. However, religion can also drive feelings of shame and guilt over certain behaviours and can be a source of struggle and distress.

The academics also say the US is particularly interesting to study because its citizens are generally more religiously inclined than those of other Western nations.

Previous studies have found Millennials show decreasing empathy, greater personal as opposed to global fears, increasingly positive self-views and decreasing trust in others and large institutions. "This pattern seems consistent with decreasing religious orientation, given that religion is often situated in institutions and focuses on more social values," the academics write. "If religion is perceived as a dominating force that restricts freedom and enforces social rules, this will be linked with a decline in religious involvement." Other studies have also linked individualism to agnosticism.

The academics say that compared to the early 1970s, four times as many adolescents report that their mother had no religious affiliation, and more than twice as many reported that their father had no religious affiliation. The gap between students' affiliation and parents' affiliation has grown, suggesting that more students grew up without religion and that more are abandoning their parents' religion when they leave home for college.

It says religious organisations are rapidly losing the youngest generation of Americans.

"Most still have some religious involvement, but significantly more are not involved with religion at all. This is noteworthy because religion is often considered a major part of social identity and transmits moral values through a sense of community.

"Many people turn to religion as a meaning system and a source of coping resources and social support. With religious orientation declining, fewer young people will have these resources," it says.

Given the important role that religion has traditionally played in the development of young people, these changes are unlikely to be without consequence for the future, the report adds.