Reddit reviews The Churching of America, 1776-2005: Winners and Losers in Our Religious Economy

For quantitative analysis of American Christianity, see Stark and Finke, The Churching of America.

For narrative history of the rise of contemporary evangelicalism as a right-wing political entity, see Darren Dochuk, From Bible Belt to Sunbelt; and Daniel Williams, God's Own Party: The Making of the Christian Right.

On how Christians dealt with the issue of slavery, see Mark Noll, The Civil War as Theological Crisis.

But to give my opinion (studied this in grad school), no, that's horseshit. He's just making up something that allows him to reduce cognitive dissonance.

Here is a link to the book. Read the reviews. It is not one of those that has the religious people giving it 1 star and nonreligious 5 stars. Instead they all rate it 3 stars and over with a pastor or 2 saying it is a must read for clergy.

https://www.amazon.com/Churching-America-1776-2005-Winners-Religious/dp/0813535530/ref=nodl_

Stark and Finke's work here is particularly good. See, inter alia, this book and for a particularly "economic" explanation, this other book that focuses on the American religious experience.

It's not that surprising. If you look at the Pew Research reference (footnote, p14) to the book, the statistic is "17% of Americans were members of a congregation." That's a big difference to being atheist or agnostic. There would be a lot of Christians not members of a single congregation, as well as many Deists since this was towards the end of the Rationalist Movement. Furthermore, Evangelicalism -- largely a reaction to all this anti-church sentiment -- did not even start until the 18th century. They came to the US because they were small minority groups.

Without looking at the statistics that Finke and Stark are talking about, it's really hard to say how they got their numbers. Is it including slaves in the South? That would really throw off the count.