Martin Luther famously nailed his 95 Theses to the door of the Castle Church in Wittenberg, Germany, on October 31, 1517. This act is considered the catalyst for the Protestant Reformation, challenging the Catholic Church's practices, particularly the sale of indulgences. Luther's theses articulated his concerns about corruption within the Church and called for a return to biblical teachings. This bold declaration quickly spread throughout Europe, sparking intense theological debates, leading to the establishment of various Protestant denominations, and significantly altering the religious landscape of the continent.