“God created man in His image: in the image of God He created him; male and female He created them.” Thus reads verse 27 of the first chapter of Genesis, one of the most important lines ever written in history. The Hebrew phrase rendered as “in God’s image” is b’tselem Elohim, and that is the title of a new book that traces the extraordinary career of this concept, known in Latin as imago Dei, throughout the course of Western civilization.

Written by Tomer Persico, a research fellow at the Shalom Hartman Institute, the book is the biography of the idea that all human beings—not just kings or heroes—are created in the image and likeness of God.

At the heart of the book is a deep irony: the religious idea of imago Dei contains within it the seeds of secularization; this religious innovation developed into a concept that would marginalize religion itself. The very emphasis on individual conscience and human equality that Judaism and Christianity cultivated eventually led to further questioning of law, and then authority, and then even the disciplines of religious life. That is, over the course of millennia, one of God’s pronouncements led some to question God’s providence and even God’s existence.

Now, if you’re listening as an orthodox believer or theological traditionalist, you may be tempted to object: surely modern secularism represents a betrayal of the biblical depiction of the human condition, not an outgrowth of it, and there is much truth to that position. But Persico’s argument is directed primarily at the committed liberal democrat who believes deeply in individual rights, human dignity, and equality, but who may not realize where these convictions come from. To that person, Persico seems to be arguing: even you, especially you, are an inheritor of a biblical idea. Your deepest moral commitments didn’t spring from nowhere. They have a genealogy that begins in Genesis.

On today’s podcast Mosaic’s editor Jonathan Silver sits down with Persico to discuss what all this implies.