Essayist and biographer Alan Jacobs introduces us to the world of original sin, which he describes as not only a profound idea but a necessary one. As G. K. Chesterton explains, "Only with original sin can we at once pity the beggar and distrust the king."

Do we arrive in this world predisposed to evil? St. Augustine passionately argued that we do; his opponents thought the notion was an insult to a good God. Ever since Augustine, the church has taught the doctrine of original sin, which is the idea that we are not born innocent, but as babes we are corrupt, guilty, and worthy of...