On this day in 1517, Martin Luther posted his 95 Theses on the Power and Efficacy of Indulgences on the door of the Castle Church of Wittenberg in Germany. This act is generally credited as the beginning of the Protestant Reformation.
Luther, a Catholic priest and professor of theology wrote the theses in protest to numerous frustrations with the Catholic Church, including indulgences and the practice of them being sold in place of confession. In 1520, Pope Leo X demanded that Luther retract his writings. He refused and was excommunicated from the church.
By that time, Luther’s 95 Theses had been reprinted all over Europe and he had numerous followers, known as Lutherans. This new form of religion launched all of the protestant denominations.