This report seeks to answer the question: What might the religious makeup of the United States look like roughly 50 years from now, in 2070, if recent trends continue? We try to address this not with sweeping predictions or grand theories, but with mathematical projections that combine techniques standardly used in demography (the study of human populations) with data we have collected in surveys on religion.
Demographers project the growth or shrinkage of populations based on factors such as age, sex, fertility, mortality and migration. For religious populations, projections also need to include data on “switching” – voluntary movement into and out of religious groups. Finally, the shifting sizes of U.S. religious groups depend partly on rates of religious transmission – whether parents pass their religious identity on to their children. In this report, Pew Research Center has incorporated estimates of “intergenerational transmission of religion” into our projections for the first time.
Switching rates are estimated based on responses from more than 15,000 adults to two questions posed in a 2019 Pew Research Center survey: “In what religion, if any, were you raised?” and “What is your present religion, if any?” Results were weighted to the Center’s National Public Opinion Reference Survey, conducted by mail and online in 2020. Long-term cohort trends in switching (going back to the 1970s) come from two similar questions in the long-running General Social Survey: “In what religion were you raised?” and “What is your religious preference?”
Shifts in religious identity, or switching, are concentrated among young adults. During earlier childhood years, a parent’s religion (or lack thereof) is often, but not always, transmitted to a child. Rates of transmission for three identity categories (Christian, other religion, and religiously unaffiliated) are estimated based on the percentages of teens (ages 13 to 17) who shared their mother’s religious affiliation in a 2019 survey of 1,811 pairs of U.S. parents and teens. These observed patterns are used to model whether future generations of newborn children inherit their mother’s religion.
Group differences in fertility (the number of children women tend to have), migration and age structures also drive change. Fertility differences by religion are based on the National Survey of Family Growth, while the average U.S. fertility rate used in each period is based on the 2019 revision of United Nations World Populations Prospect data. Migration data comes from the UN. Religious composition by age and sex groups is based on Pew Research Center’s American Trends Panel. We estimate the religious composition of children based on the religious composition of young adults, and fertility patterns.
The various input data is used in projection models to illustrate what the future religious composition of the U.S. might look like under a range of hypothetical scenarios. See Methodology for more information on inputs and modeling.
Since the 1990s, large numbers of Americans have left Christianity to join the growing ranks of U.S. adults who describe their religious identity as atheist, agnostic or “nothing in particular.” This accelerating trend is reshaping the U.S. religious landscape, leading many people to wonder what the future of religion in America might look like.
What if Christians keep leaving religion at the same rate observed in recent years? What if the pace of religious switching continues to accelerate? What if switching were to stop, but other demographic trends – such as migration, births and deaths – were to continue at current rates? To help answer such questions, Pew Research Center has modeled several hypothetical scenarios describing how the U.S. religious landscape might change over the next half century.
The Center estimates that in 2020, about 64% of Americans, including children, were Christian. People who are religiously unaffiliated, sometimes called religious “nones,” accounted for 30% of the U.S. population. Adherents of all other religions – including Jews, Muslims, Hindus and Buddhists – totaled about 6%.1
Depending on whether religious switching continues at recent rates, speeds up or stops entirely, the projections show Christians of all ages shrinking from 64% to between a little more than half (54%) and just above one-third (35%) of all Americans by 2070. Over that same period, “nones” would rise from the current 30% to somewhere between 34% and 52% of the U.S. population.
What is religious switching?
Switching, which in some cases could be described as religious conversion, is defined in this report as a change between the religion in which a person was raised (in childhood) and their present religious identity (in adulthood).
Current rates of switching are based on responses from more than 15,000 adults to two questions posed in a 2019 Pew Research Center survey: “In what religion, if any, were you raised?” and “What is your present religion, if any?”
In many cases, switching does not happen in a single moment. Religious “nones” often describe their disaffiliation as a gradual process, and some may never have felt a strong connection to a religious identity, even though they describe themselves as having been raised in a faith tradition.
However, these are not the only possibilities, and they are not meant as predictions of what will happen. Rather, this study presents formal demographic projections of what could happen under a few illustrative scenarios based on trends revealed by decades of survey data from Pew Research Center and the long-running General Social Survey.