The Protestant Reformation was a series of events that happened in the 16th century in the Christian Church. Because of corruption in the Catholic Church, some people saw that the way it worked needed to change. People like Erasmus, Huldrych Zwingli, Martin Luther and John Calvin saw the corruption and tried to stop it. This led to a split in the church, into Catholics and various Protestant churches. "The Protestant reformation triggered the Catholic Counter-Reformation."