Protestant_Reformation The Protestant Reformation was a Christian reform movement in Europe which is generally deemed to have begun with Martin Luther's Ninety-Five Theses although a number of precursors such as Johannes Hus predate that event. As a historical period, the Reformation is considered to have ended with the Peace of Westphalia in 1648; however, many of the denominations that arose during that period continue to exist and Protestantism constitutes one of the branches of Christianity today.