By some key measures, Americans ages 18 to 29 are considerably less religious than older Americans. Fewer young adults belong to any particular faith than older people do today. They also are less likely to be affiliated than their parents' and grandparents' generations were when they were young. Fully one-in-four members of the Millennial generation – so called because they were born after 1980 and began to come of age around the year 2000 – are unaffiliated with any particular faith.
Indeed, Millennials are significantly more unaffiliated than members of Generation X were at a comparable point in their life cycle (20% in the late 1990s) and twice as unaffiliated as Baby Boomers were as young adults (13% in the late 1970s). Young adults also attend religious services less often than older Americans today. And compared with their elders today, fewer young people say that religion is very important in their lives.
Read the full report Religion Among the Millennials on the Pew Forum on Religion & Public Life's Web site.