Martin Luther King Jr. The reformation began within the Catholic Church . On Oct. 31, 1517 , Martin Luther a professor and a monk of theology, posted his 95 Theses on the Castle Church in Wittenberg, Germany . This theses were series that attacked the sale of indulgences . Luther criticized what he considered other abuses in the church . Luther taught that God justifies human beings . What Luther meant was that God makes them righteous through His kindness to the people . In Jan. 1521, Pope leo X excommunicated Luther and declared him a heretic . Emperor Charles V and the members of the imperial diet ordered Luther to appear before the diet in the Wor