Check out the new U.S. demographic data from the Pew Research Center which show that the percentage of Americans declaring affiliation with a particular religion has declined sharply since 2007 (//vny!://www.pewforum.org/2015/05/12/americas-changing-religious-landscape/).
Americans identifying as Christian dropped from 78.4% in 2007 to 70.6% in 2014. Those describing themselves as atheist, agnostic, or simple having no affiliation took up most of the slack, rising from 16.1% to 22.8%. Members of non-Christian faiths collectively rose from 4.7% to 5.9%.
Despite the overall decline, the demographics within the Christian group are getting much more racially and ethnically diverse. The willingness of respondents to marry outside their religious affiliation is also on the rise. The median age of unaffiliated adults is dropping, while the median ages of mainline Protestants and Catholics are rising.
The study estimates that 85% of adults age 70 and over are Christian, while only 56% of adults ages 18-24 are Christian. They also say that each individual generation has shown a slight decrease in religious affiliation compared to their statistics in 2007.