Martin Luther was a German monk who, in 1517, published his Ninety-Five Theses, which criticized the Catholic Church’s sale of indulgences and other abuses. By posting his Theses on the door to the church in Wittenberg, Luther inaugurated the Protestant Reformation, perhaps the greatest schism in Western Christianity and the beginning of the modern world. Luther’s actions caused shockwaves throughout Europe, inaugurating a period of religious change and religious warfare that did not end until the Treaty of Westphalia ended the Thirty Years War in 1648.
At the same time that Luther was separating from the Church in Germany, Ulrich Zwingli in Switzerland was attempting the same, although his supporters thought Lutherans were too conservative. This was the foundation of the Anabaptists, of which John Calvin was perhaps the most famous advocate.
One of Luther’s chief contributions to Christianity was his German translation of the Bible. He believed that all Christians should be able to access the text and that it was the final religious authority, not the Pope. Luther’s translation, along with numerous religious tracts, coming shortly after the invention of the printing press, was also a turning point in making literacy widespread throughout Europe. However, the Reformation also plunged Europe into over a century of religious based warfare, which culminated in the Thirty Years War.