The concept of zeal is a complex one in Scripture. It is often linked in the Old Testament to physical violence against those who opposed God and his covenant with Israel. This is the kind of zeal demonstrated by Saul the Pharisee in his persecution of the infant church. The zeal of Paul the apostle, on the other hand, had been transformed by the cruciform zeal of Christ. An appreciation of this transformation sheds new light on some exegetical cruxes in Paul’s writings. It also highlights key differences between the old and new covenants and between proper and misplaced religious zeal.