The posting of Martin Luther's 95 Theses marked a significant turning point in Christian history. In the early 16th century, the Catholic Church was seen as a powerful institution, with immense influence over spiritual and political matters in Europe. Amidst growing discontent with certain practices, particularly the sale of indulgences—a practice that promised forgiveness of sins in exchange for money—Luther, a devout monk and theologian, sought to initiate an academic discussion on these issues. On October 31, 1517, he nailed his theses to the Castle Church door in Wittenberg, a common practice for communicating scholarly ideas at the time. Luther's chief assertion was that salvation could not be purchased and that faith alone (sola fide) was the path to salvation. His 95 Theses quickly spread beyond Wittenberg, thanks in part to the recent invention of the printing press, reaching a wide audience throughout Europe. The impact was immediate, igniting widespread debate and leading many to question the authority and practices of the Catholic Church.

Luther's actions were not without risk; they challenged the established power of the Church and threatened the social order of the time. The ensuing movement, called the Protestant Reformation, attracted followers who sought to reform various aspects of religious life, including church governance, liturgy, and the interpretation of scripture. While Luther initially sought reform rather than schism, his critiques ultimately contributed to the formation of new Christian denominations that would branch off from Catholicism. The Reformation catalyzed significant political and cultural upheaval across Europe, leading to wars, the establishment of Protestant state churches, and significant shifts in power dynamics between church and state.

Additionally, Luther’s emphasis on returning to Scripture and promoting education in theology led to the rise of universities and lay participation in religious life. The 95 Theses not only called for reform within the Catholic Church but also encouraged the development of a personal connection to faith that was independent of clerical authority. Luther’s act effectively paved the way for changes in religious practices that would resonate through centuries, fostering a legacy that shaped modern Christianity.