Protestant Christianity began with one stubborn monk in 1517. Now it covers the globe and includes almost a billion people. On the 500th anniversary of Luther’s theses, a global history of the revolutionary faith that shaped the modern world.Five hundred years ago an obscure monk challenged the authority of the pope with a radical vision of what Christianity could be. The revolution he set in motion inspired one of the most creative and destructive movements in human history. It has toppled...