In Public Confessions (Univ. of North Carolina, Oct. 5) historian Davis considers how prominent religious conversions changed American politics.

You write that religious conversions in the post-WWII era “galvanized associations between spiritual, sexual, racial, and political authenticity.” Could you elaborate on that?

This gets at the heart of what the book is about. I found that religious conversion became a test of political authenticity in the mid-century U.S. It became a way for people to say who they really were at a time when there was massive anxiety about fascism, communism, popular culture, and mass culture—all these different forces that might take over the individual’s mind. Where communism, during the Cold War, was often seen as an external threat—an ideology that might create warfare or a military conflict for the U.S.—at the same time there were fears insidious ideas might take over the individual mind. Religious belief was part of that conversation.

How does that relate to sexuality or race?

What I found was that this question about where free will begins and ends” also raises questions about sexuality. Because at the time, homosexuality was defined in federal law as a condition that made people mentally unstable, that was associated with deceit or subterfuge. So sexual authenticity—being truly who you were—became complicated if you wanted to have a role in politics. You saw several people who had been communists who then wanted to affiliate with the political right need to perform very publicly that they were heterosexual. And this continues into the 1970s in the way that some conservative evangelical Protestants defined the true experience of being born-again with a very overt narrative about the convert being a heterosexual. And for racial authenticity, the conversion stories of nonwhite people received a degree of scrutiny I found surprising. The more I looked into it, the more I saw a broader culture that discredited certain kinds of personal truths.

Have highly publicized religious conversions become less contentious?

In the last 20 years, what I’ve seen are many stories about converts to Islam, particularly young people who have become radicalized, and the narrative becomes “brainwashing.” The irony is that religious identification has become far more fluid in the U.S. since the ’80s and ’90s. There are far more people who identify as both Jewish and Buddhist, for example. And this culture of being spiritual seekers is far more accepted. The most recent surveys of religious affiliation show that self-defined Christians have declined, and the numbers of unaffiliated or nonbelievers increased. So, in a sense, for the right, having a Judeo-Christian authenticity has become more important even as religious identification has become less politically significant.