The Protestant Reformation, often referred to simply as the Reformation, was the schism within Western Christianity initiated by Martin Luther, John Calvin, Huldrych Zwingli and other early Protestant Reformers.Although there had been significant earlier attempts to reform the Roman Catholic Church before Luther — such as those of Jan Hus, Peter Waldo, and John Wycliffe — it is Martin Luther who is widely acknowledged to have started the Reformation with his 1517 work The Ninety-Five Theses.