Who initiated the Protestant Reformation in 1517 and criticized Catholic beliefs?

The Protestant Reformation was initiated by Martin Luther in 1517 when he famously nailed his Ninety-Five Theses to the door of the Castle Church in Wittenberg, Germany. This document criticized various practices of the Catholic Church, particularly the sale of indulgences, which Luther viewed as corrupt and contrary to biblical teachings. He argued for a return to scripture as the sole authority for Christians, emphasizing faith alone for salvation rather than the church's rituals and sacraments. Luther’s actions not only sparked widespread religious reform across Europe but also led to the establishment of various Protestant denominations that sought to separate from Catholic doctrine and practice. His critiques and reformative ideas laid the groundwork for a significant shift in Christian thought and the structure of Western Christianity.