Martin Luther posted the 95 theses on the door of the Wittenburg Cathedral. The theses talked about unjust and issues he believed the Catholic Cathedral had. His actions started the Protestant Reformation. He was soon excommunicated by the church, but managed to gain a following.
The society of Jesus (also known as the Jesuits) were people trying to convert others back to the Catholic because of all the people that were following Luther's way of Christianity.
Another part of the Reformation included King Henry VII from the Catholic Church forms his own church; the Church of England. He created this church after the Pope wouldn't allow Henry to divorce his wife and marry her story. With his new church he was allowed to do so. Soon all of England turned into his church