During the last decade, one in 20 Americans has shifted from identifying with a religion to claiming “nothing in particular.” And of any position on religion, this “nothing in particular” group is the least likely to hold at least a bachelor’s degree.

Those are just two of the many findings that jump from the page in Ryan Burge’s new book, The Nones: Where They Came From, Who They Are, and Where They Are Going (Fortress Press). Sociologists categorize the “nothing in particular” group, along with atheists and agnostics, as “nones.”

Today, as many Americans don’t affiliate with any church as belong to a major religious group. We’re talking about one of the largest religious trends, if not the largest, in the last 40 years. Burge’s book seeks to explain how these so-called nones grew from statistically irrelevant to around one-quarter of the entire American population.

Burge is an assistant professor of political science at Eastern Illinois University. And he’s also been a pastor in the same American Baptist church for the last 13 years. So his work goes beyond the descriptive into the prescriptive. For example, he observes that among the nones, Christians should focus on this “nothing in particular” group, which is open to returning to religion.

He joined me on Gospelbound to discuss the implications of his findings for evangelicals, for Black Protestants, for the mainline, and for politics. I asked him why so many Americans left the church between 1991 and 1996 and his best guess at the most significant cause behind this trend.