A new analysis from the Pew Research Center suggests that decisions about faith are often made early in life — and once made, they tend to last.
The research shows that more than a third (35%) of US adults no longer identify with the religion in which they were raised.
Most of those who leave the faith do so before the age of 30, highlighting young adulthood as a pivotal period for religious change.
Despite this shift, religion remains a stable anchor for many. A majority of Americans (56%) continue to affiliate with the religion they were raised in, while 9% did not have a childhood faith and remain unaffiliated today.
The findings draw on data from Pew’s 2023–24 Religious Landscape Study, which surveyed 36,908 US adults, alongside a subsequent Center’s American Trends Panel (ATP) survey of 8937 adults carried out in May 2025 to better understand why people stay, leave, or never affiliate at all.
Among adults who continue to identify with their childhood religion, personal belief and spiritual fulfilment outweigh social or cultural reasons.
Nearly two-thirds (64%) say belief in their religion’s teachings is a major reason they remain affiliated.
Similar numbers point to their faith offering spiritual fulfilment (61%) or providing purpose in life (56%).
By contrast, a smaller share report that community ties (44%), custom (39%), or familiarity (39%) are decisive factors.
Motivations vary by faith tradition. Protestants (70%) who remain in the faith most commonly state belief in doctrine, while Catholics (54%) are slightly more likely to emphasise spiritual fulfilment.
Jewish respondents, meanwhile, are more likely to highlight tradition (60%), community (57%), and family heritage as central to their religious identity.
For those who have left their childhood religion — including people who switched to a different faith (10%) and those who are now completely unaffiliated (20%) — belief again plays a central role, but in the opposite direction.
Many say they lost confidence in the doctrines they were raised with (46%), while others report that religion simply became less significant over time (38%) or that they slowly disengaged from their faith (38%).
Around a third (34%) also point to disagreements with religious stances on social or political matters, while 32% took issue with misconduct allegations among religious leaders.
The reasons differ depending on where people land. Nearly half (48%) of those who join a new religion often describe feeling drawn or “called” to a different faith, while 45% stated seeking deeper spiritual fulfilment.
Those who become religiously unaffiliated are more likely to say they lost belief altogether or no longer felt religion mattered in their daily lives.
Nearly three in 10 US adults (29%) now identify as atheist, agnostic, or “nothing in particular” — a group often referred to as religious “nones.”
About three-quarters (73%) of people who grew up as “nones” remain religiously unaffiliated as adults, while 26% identify with a religion today.
Among the nones, the most frequently mentioned reasons for non-affiliation include holding that morality does not require religion (78%), doubting religious doctrines (64%), and feeling that spirituality can exist without organised religion (54%).
Around half also express distrust of religious institutions or leaders. A smaller number (6%) describe religion as harmful, while others say they remain open to belief but see no need to formally belong to a religious group.
The study finds that upbringing plays a powerful role in shaping adult religious identity.
A majority (84%) of adults who recall favourable childhood experiences with religion are far more likely to remain in that faith later in life. By contrast, 69% of those who describe negative early experiences are significantly more likely to become unaffiliated.
Household religious intensity also matters: 82% of people brought up in strongly religious households show a greater likelihood of staying within their childhood faith than those raised in less observant settings (47-77%).
Political identity and age further shape outcomes. Nearly three quarters (73%) of Republicans who grew up in a religious household remain affiliated, compared to over half (56%) of Democrats.
Younger adults are far more likely than older generations to have no religious affiliation at all.
Across traditions, religious change most often happens young.
The vast majority of Americans (85%) who adopt a different faith or leave faith altogether say they did so by age 30, with nearly half (46%) making the change before adulthood.
Those who leave religion entirely are more likely to do so earlier than those who move from one faith to another or join a religion after being raised without one.
Once these shifts occur, they are largely enduring.
Pew’s researchers note that while some Americans do change religious paths later in life, early adulthood remains the most decisive period for belief, belonging and identity.
