The Ninety-Five Theses on the Power of Inulgences, commonly known as The Ninety-Five Theses, were written by Martin Luther in 1517 and are widely regarded as the primary catalyst for the Protestant Reformation. Luther used these theses to display his displeasure with the Church's sale of indulgences, and this ultimately gave birth to Protestantism. Luther's popularity encouraged others to share their doubts about the Church and to protest against its medieval ways; it especially challenged the teachings of the Church on the nature of penance, the authority of the pope and the usefulness of indulgences. They sparked a theological debate that would result in the Reformation and the birth of the Lutheran, Reformed, and Anabaptist traditions within Christianity.