I recently read my friend and Baylor colleague Alan Jacobs’s erudite and accessible book Original Sin: A Cultural History. This book is a model of the kind of Christian apologetics that might actually reach non-Christians. Humankind’s flawed nature is an intractable problem that has vexed prominent observers from the ancient Greeks to the “New Atheists.” But explaining the reasons for that flawed nature has been trickier than observing it. Jacobs does not assume that his readers are Christians, but he does suggest that the Christian explanation for humanity’s propensity to sin is the best explanation of all.

Learned observers, including some liberal theologians, have been trying to jettison the doctrine of original sin (or our sin nature inherited from Adam) for millennia. But they haven’t come up with any more satisfactory explanations than the Christian one. That explanation was best advanced by Augustine and his theological descendants.

You must hold five distinct beliefs in order to affirm the Augustinian anthropology, Jacobs writes.

You must believe that everyone behaves in ways that we usually describe as selfish, cruel, arrogant, and so on. You must believe that we are hard-wired to behave in those ways and do not do so simply because of the bad examples of others. You must believe that such behavior is properly called wrong or sinful, whether it’s evolutionarily adaptive or not. You must believe that it was not originally in our nature to behave in such a way, but that we have fallen from a primal innocence. And you must believe that only supernatural intervention, in the form of what Christians call grace, is sufficient to drag us up out of this pit we’ve dug for ourselves. (If we add to this list a sixth belief, that through the death of Jesus Christ God has provided this intervention, then we have the core of the theology that complements the anthropology. But that hasn’t been the concern of this book.)

Once the model is laid out in this way, with these five interlocking and necessary propositions, it may be surprising that anyone has ever affirmed it. Yet millions have, and millions more will. Perhaps that’s because each of these positions is well warranted by careful observation of human beings.

There’s a lot more to recommend in this book, not least Jacobs’s remarkable reading across many different times and places on the theme of sin and fallenness. It also displays a Christian willingness to speak to an interested non-Christian audience on their own terms. We must remember that the truths of the gospel will often seem implausible to outsiders, especially those who did not grow up in a Christian context.

Too often, pop Christian apologetics proceeds with the assumption that Christianity is so self-evidently true that you’d have to be stupid or dishonest to reject it. This is a bad approach for a number of reasons, not least that it implies that believers saw the light because they were smart enough to see it. For those of us with a high view of grace, such a smug view will not do.

Jacobs follows in a much healthier and theologically sound tradition of those such as C. S. Lewis who say to the non-Christian world, as it were, “I know that Christianity’s claims may sound crazy at first. But what if they actually make sense of life’s most besetting problems?”