Martin Luther was a German theologian and monk who played a pivotal role in initiating the Protestant Reformation during the 16th century. There were several key actions and events associated with Luther’s role in starting the Reformation:

1. Ninety-Five Theses: In 1517, Luther famously wrote and nailed to the door of the Castle Church in Wittenberg, Germany, the Ninety-Five Theses. This was a list of grievances and theological propositions challenging the practices of the Catholic Church, particularly regarding the sale of indulgences (a way for someone to pay money as a penalty which, supposedly, absolved them of past sins and/or released one from purgatory after death).
2. Opposition to Indulgences: Luther’s strong objection to the sale of indulgences sparked significant debate and criticism within the Catholic Church. His writings and teachings on this topic gained widespread attention and debate.
3. Translation of the Bible: Luther was instrumental in translating the Bible from Latin into German, making it accessible to everyone, including the ordinary person. This helped to promote biblical literacy and allowed for individuals to read and interpret scripture for themselves, without the need of a priest.
4. Excommunication and Diet of Worms: In 1521, Luther was called to stand at the Diet of Worms, a major assembly of political and religious leaders. He was asked to recant his beliefs, yet he refused. Luther stood boldly and stated, “Here I stand, I can do no other.” Due to this, he was excommunicated by and from the Catholic Church.
5. Formation of Lutheran Church: Luther’s teachings and reforms gained a significant following. This resulted in the establishment of the Lutheran Church as its own distinct Christian denomination. His theological ideas, reforms, and writings built the foundation for Protestantism.

Martin Luther’s actions and teachings ignited a major movement that aggressively challenged the religious and political authority of the time. This lead to significant changes in Christianity and the establishment of various Protestant traditions around the globe.