I can't give a complete review, since I only read the first half of the book, which was on how Protestantism changed into post-Protestantism, and the concluding chapter. The other half was on what's happened to Catholicism in our national life, but I was less interested in that.
I liked this book, because it addressed something I've been seeing for years, but couldn't fully explain: Why people who are politically active (though I should say liberals in particular) are so adamant about supporting a political position without seeming to have the ability to back it with anything substantial, other than a seeming faith that they're right. They are unwilling to listen to a substantial argument about why they may be addressing societal problems in a way that's counterproductive, preferring instead to essentially call anyone who disagrees evil, and in some cases take punitive actions against them for their views. It occurred to me that this seemed like religious behavior--a "secular religion." It seemed puritanical as well.
Bottum's analysis agreed with mine: It is religious behavior, but without an identified religion. Bottum calls it "post-Protestantism." He explains from a historical and sociological perspective how this came about, that it came out of Mainline Protestantism, through a few different theologians, philosophers, and religious leaders.
The main subject of this part of his book is a man named Walter Rauschenbusch, a Protestant theologian who created a social religious movement in the early 20th century. Bottum says if you read Rauschenbusch's books, "A Theology for the Social Gospel," and "Christianity and the Social Crisis," you will see the character of today's post-Protestants. The key difference between what Rauschenbusch advocated and the post-Protestants is that Rauschenbusch believed in the divinity of Jesus Christ, but today's post-Protestants don't even think about Jesus. They are the people who say of themselves that they're "spiritual, but not religious." In their minds they've left the "religious tommyrot" behind. Bottum says they maintain the same religious character as their Protestant ancestors, but regarding public social issues, rather than regarding their own souls. They reject their ancestors' self-consciousness, and faith in Christianity. Instead they insist they have a public consciousness, and what they fight against and attack is all the historical evils they perceive in this world, including Christianity. Yet still, they seek a kind of spiritual salvation, as their ancestors did, but by advocating for social causes in the political process. They have a sense of themselves that they have been redeemed by transforming their personality, and through a recognition of society's historical social evils. "Sin" to them exists as "demons and ghosts," as Bottum characterize it, in an odd sort of way. If you talk to them, they won't describe themselves as "redeemed," nor will they profess a belief in "demons and ghosts," but it's hard to characterize their beliefs about themselves and the world any other way, because there is no rational explanation for it. They have no justification for their behavior other than their recognition of these social evils, and the peer support they receive from their politically ideological community.
Bottum could be criticized for imposing a religious label on what he sees, but he uses a historical, and sociological perspective (I would argue he assumes some anthropological knowledge as well) to justify it. In my mind, it's difficult to argue with it, because I came to the same conclusion before I read his book. However, one could charge me with engaging in confirmation bias, because Bottum does not support his argument well. He gave me background I did not know, and perhaps others could provide a more accurate account that contradicts his, or fills in details he missed.
Bottum seems to propose that this was a natural process of modernization, but in his conception this contradicts the "founding forces" that formed this country. He explores the Secularization Hypothesis, that as societies modernize they naturally become more secular, and religion falls by the wayside. In the final chapter, he argues that this move toward "secular religion" is troubling, because it's not organized religion in the sense that that term used to mean, and may imperil the entire American project. He accepts as axiomatic that America was founded on a "three-legged stool" of religion, democracy, and capitalism, each creating tension on the other two. He says if (organized) religion is removed, then all we have is democracy and economics fighting it out, and there is nothing moderating them other than each other. In a strange sort of way he uses the growth of religiously extremist movements in the developing world as a "hopeful" sign that the Secularization Hypothesis may be flawed, but he doesn't offer an alternative hypothesis for why Protestantism collapsed, other than a few theories on social forces. As I read, I kept wondering whether this secularization was encouraged by political forces inside and outside our country, but he doesn't address that idea.
A couple large criticisms I have is he talks about five or so people who are his examples of post-Protestants. He gives them fictional names, and talks briefly about their backgrounds, but he doesn't really tie them in to the historical narrative he's talking about. He just assumes you'll trust him that the connection exists. He doesn't let the reader in on the conversations he had with them, except by his own paraphrasing, so that we can get a sense of who these people are as individuals. They may as well be archetypes, which is not very satisfying, since he was trying to write a work of non-fiction.
The historical and sociological perspective he offers is interesting and persuasive, but I think that's as far as it goes. Sociology is not regarded as a hard science, and you do not get hard science here. He wrote it almost as if the reader would recognize many of the points he makes from reading prior background material, or having experienced the history he talks about, but he doesn't give the reader the means to fill in that background in all its detail.
He could've made his argument more substantial, I think, if he had explained the anthropological perspective on religion, and then tied it into the interviews he had with the people he cited, and then his historical narrative, giving lots of footnotes along the way that would help fill in the background detail. Instead one is simply expected to trust that the author's analysis is sound, and that you will agree with him if you look at the same few historical sources he cites. It's an easy read, not a scholarly work, but I think that leaves him open to a lot of criticism, and may cause people to dismiss his argument altogether.