Answer:
Martin Luther.
Step-by-step explanation:
Martin Luther was a German theologian, a monk, an author, etc. among many other titles. He was famous for his "Ninety-Five Theses" which critiques the selling of indulgences by the Catholic Church. He would later be the influence behind the increase and spread of secular democracy in the Christian world.
Luther was against the practice of clergy selling plenary indulgences to the public. These indulgences are a sort of 'forgiven pass' for believers to get to heaven with lesser 'punishments'. This means that buying indulgences allow a person to get fewer punishments after death and get to heaven. Martin Luther believed that faith alone is the only requirement to get to heaven and not such indulgences. He famously printed his Ninety-Five Theses and nailed it to the Church door.