The U.S. religious landscape is already in the midst of some dramatic changes when it comes to the growth or decline of people with certain religious identities. And while it is impossible to predict exactly how that landscape will shift in the future, some key demographic factors — particularly age — can provide a clue as to how things might unfold in the coming decades.
For example, religious groups whose members are younger may be more likely to grow, not only because those members will live longer, but also because more of them are still of childbearing age (and thus have a greater chance of passing on their religion to their descendants).
With this in mind, some of the groups that have already been growing in recent years may be primed for continued growth. This includes people with no religious affiliation: The median age of adults who say their religion is “nothing in particular” is 38, while for atheists and agnostics it is 34.
Overall, these three groups together (often called religious “nones”) have a median age of 36 – fully a decade younger than the median age of U.S. adults overall (46), according to data from our 2014 Religious Landscape Study.
Members of some non-Christian faiths also are very young – U.S. Muslims and Hindus in the survey each have a median age of 33. About four-in-ten Muslim adults in the U.S. are under the age of 30, and nine-in-ten Hindu adults are under 50.