When Martin Luther published his 95 Theses in October 1517, he had no intention of starting a revolution. But very quickly his criticism of indulgences became a rejection of the papacy and the Catholic Church emphasizing the Bible as the sole authority for Christian faith, radicalizing a continent, fracturing the Holy Roman Empire, and dividing Western civilization in ways Luther--a deeply devout professor and spiritually-anxious Augustinian friar--could...