The Sinfulness of Sin, first published as The Plague of Plagues, is Ralph Venning's sustained examination of sin itself. Venning defines sin as contrariety to God and then traces what that means: its offence against each divine attribute, its injury to the sinner and to others, its consequences in this life and the next, and the aggravations that make some sins worse than others. The book closes by turning to the remedy in Christ.

Part of Banner of Truth's Puritan Paperbacks, a series that puts the shorter works of the Puritans into print at a price that makes them worth giving away. Venning wrote in the aftermath of the Great Plague, and the parallel he draws is deliberate. The book is bracing rather than comfortable, and its value lies in restoring weight to a word that modern usage has made trivial. Readers who find the gospel unremarkable often find it otherwise after this.