Miroslav Volf, the leading Protestant theologian of his generation, has written a book that might serve as a model for how to do "public theology"—a book that can be read with profit by any thoughtful Christian. Free of Charge: Giving and Forgiving in a Culture Stripped of Grace is a sustained examination of the scandalous truth at the heart of the gospel: "God's forgiveness is indiscriminate." We've become dulled to this truth, Volf observes. We need to recover it again and again.

Don't linger over the reference to a "culture stripped of grace" in the subtitle. That's one of the book's very few concessions to a marketing department's idea of relevance. Volf refers at the outset to "a larger pattern of what we may call the gracelessness that is slowly spreading like a disease through many of our cultures," but the specific example he gives—a rude American cop—will strike many readers as underwhelming, and he makes no effort to mount a historical argument. What he's interested in is a perennial human condition—and the way in which God's graciousness allows us to enter a very different "culture," a community of love.

Exploring the implications of God's great gift with a subtle dialectical intelligence and a winsome voice—the stories from his life that give the book a powerful personal dimension will stay with readers a long time—Volf is in constant conversation with Martin Luther. Indeed, Free of Charge could be described as a return to the wellsprings of the Reformation.

My copy of the book is a thicket of Post-it notes marking passages to return to: "Naked need is the occasion for God's giving, not a need adorned with the clean, elegant robes of respectability and good works." "There are no unforgivable ...