From a New York Times column by Jessica Gross headlined “The Largest and Fastest Religious Shift in American Is Well Underway”:

In previous stories about Americans falling away from religion, I’ve talked about why so many Americans’ religious identities now fall in the category known as “nones” when, just a half-century ago, nearly all Americans had some kind of affiliation. (It’s largely a combination of Christianity’s association with far-right politics and the fact that being unreligious has become more socially acceptable over time.)