Martin Luther (1483-1546) forged the modern alliance between individual conscience and the sovereignty of the secular nation-state. He was born into a family that had risen from peasantry into the middle class. Almost struck by lightning in a summer thunderstorm, he vowed to become a monk if his life were preserved. He joined the Augustinian monastery in Erfurt in 1505 and was ordained two years later. The Elector of Saxony, Frederick the Wise, founded a new university at Wittenberg, where Luther became a professor. Lecturing on Saint Paul’s Epistle to the Romans, Luther discovered his core doctrine: that we are justified by faith alone. No amount of religious devotion or moral action could make us good: the goodness of Christ becomes “imputed” to us by grace alone. He had always suffered from crippling spiritual anxiety, and this insight cured him.

To fund the building of St. Peter’s Basilica and to help the Archbishop-Elector of Mainz pay for his office, Pope Leo X (a Medici) authorized, in a territory neighboring Luther’s, the sale of indulgences—documents serving to remit the temporal punishment owed due to one’s sins. Luther protested the abuse of indulgences with his Ninety-five Theses of 1517. Pope Leo excommunicated him in 1520 (the year The Freedom of a Christian was written), and the Holy Roman Emperor Charles V declared Luther an outlaw at the Diet of Worms in 1521. Luther ended up advancing the Reformation by an appeal to secular rulers, rather than to the common people: this suppressed the social-revolutionary potential in his reform and folded church into state.