In 1517, Martin Luther posted his 95 Theses to the door of All Saints' Church in Wittenberg, Germany. In these theses, Luther questioned the Catholic Church's sale of indulgences to reduce punishment in Purgatory for sins and argued that faith, not works, led to salvation.
The Catholic Church's first response to his theses was to summons him to Augsburg in 1518 to argue his position before Cardinal Thomas Cajeton. The debate with Cardinal Cajeton lasted three days, and Luther refused to retract his positions, leading Luther to need to escape arrest and imprisonment in Rome.
The Catholic Church's second response was for Pope Leo X, by 1520, to issue a papal bull declaring Luther's theses to be heretical. When Luther still did not retract his positions, he was excommunicated.
A third response of the Catholic Church was for Prince Frederick III, brother of Roman Emperor Charles V, to summons Luther to appear before the Imperial Diet, meaning assembly, at the Diet of Worms, in 1521. Here, Luther was asked by Johann Eck to defend the positions in his writings, which Luther did, including his rejection of the supremacy of the pope. The Diet of Worms led to Emperor Charles V issuing the Edict of Worms, forbidding anyone to support Luther upon punishment as a heretic.
After the bloody Peasants War raged from 1524 to 1525, the Catholic Church was forced to show tolerance to the emergence of Lutheranism. However, true peace was not established between Catholics and Protestants until the Treaty of Hamburg was signed after the Thirty Years' War ended in 1648, having begun in 1618.