According to a just-issued Gallup poll, about 20 million Americans have left organized religion since 2008, bringing the estimated number of religious “nones” to about 64 million. Via Gallup:
A review of over 174,000 interviews conducted in 2015 shows that three-quarters of American adults identify with a Christian religion, little changed from 2014, but down from 80% eight years ago. About 5% of Americans identify with a non-Christian religion, while 20% have no formal religious identification, which is up five percentage points since 2008.
The downtick in the percentage of the U.S. population identifying as Christian over the past eight years is a continuation of a trend that has been evident for decades. In Gallup surveys in the 1950s, over 90% of the adult population identified as Christian, with only a small percentage claiming no religious identification at all or identifying with a non-Christian religion.
One key to the future of Christian representation in the U.S. population will be shifts in the religious identification of today’s youngest cohorts. Traditionally, Americans have become more likely to identify with a religion as they age through their 30s and 40s and get married and have children. If this pattern does not occur in the same way it has in the past, the percentage of Christians nationwide will likely continue to shrink.
Most self-identified “nones” say they still believe in God or some higher power. According to other polls, actual atheists only make up about 3% of the US population.