Prominent observers complain that public discourse in America is shallow and unedifying. This debased condition is often attributed to, among other things, the resurgence of religion in public life. Steven Smith argues that this diagnosis has the matter backwards: it is not primarily religion but rather the strictures of secular rationalism that have drained our modern discourse of force and authenticity.

Thus, Rawlsian "public reason" filters appeals to religion or other "comprehensive doctrines" out of public deliberation. But these restrictions have the effect of excluding our...