The beginning of the Reformation is typically attributed to Martin Luther, a German theologian and Augustinian monk who challenged the authority of the Roman Catholic Church. In 1517, Luther published his Ninety-Five Theses, a list of grievances against the Church's practices, particularly the selling of indulgences, which he believed to be a form of corruption. His actions sparked a religious movement that led to the Protestant Reformation and the establishment of Protestant denominations.