The famous reformer whose writings sparked the Protestant Reformation was Martin Luther. In 1517, he famously nailed his Ninety-Five Theses to the door of the Castle Church in Wittenberg, Germany, challenging the Catholic Church's practices, particularly the sale of indulgences. Luther's beliefs emphasized salvation through faith alone and the authority of scripture, rather than Church tradition. His ideas spread rapidly due to the printing press, leading to a significant religious upheaval throughout Europe. Luther's actions inspired reform movements and led to the establishment of various Protestant denominations, ultimately transforming the landscape of Christianity.