In 1517, the Christian Church was still the very heart of Western life, and the vast majority of people were devoutly religious and loyal to the Church and her traditions, even if they were aware of the serious shortcomings of their leaders. Yet, within a few short years, these same Christians were burning monasteries, reviling the pope and destroying statues, shrines and relics. What brought about this astounding transformation?

Put simply, the Reformation was as much a political revolt as it was ever a theological movement. Political expediency among many of the princes in the Holy Roman Empire made the embrace of a revolt by reformers against the prevailing social order politically and economically advantageous.

In Germany, for example, when the Lutheran revolt began and it was clear that Holy Roman Emperor Charles V was resolved to remain Catholic, German princes, knights and peasants saw the reformers as a possible means of bringing about a new Germany. With Protestantism as their creed, they might be free from the emperors, the prince-bishops and what they viewed as the chronic interference of the popes.

Socially, the collapse of feudalism and the movement of the populations to the cities had a significant impact on social cohesion. This was compounded by the lingering impact of the Black Death in the 14th and 15th centuries.

The plague had killed off as much as a third of the European population, including large numbers of the clergy, and it destabilized many communities.

The intellectual effects of humanism and Renaissance thought were also felt, quite profoundly. Having assailed Scholasticism and reduced the hierarchy to figures of scorn and satire, the humanists made inevitable the questioning of theology. The humanists brought the Bible before the European consciousness in a new way. Desiderius Erasmus, John Colet and others stressed the place of the Bible in the very essence of faith. In so doing, they prepared the way for Luther and his fellow Reformers to pay primary focus to Scripture.

To be sure, there were problems in the Church, such as the practice of selling indulgences, exemplified by the appalling and illegal actions of the Dominican Johannes Tetzel, the peddler of indulgences across Germany in the effort to raise money for Pope Julius II’s otherwise worthy project to rebuild St. Peter’s Basilica. There was also late medieval philosophy — such as that of William of Ockham — that rejected traditional Christian philosophy in favor of an individualism and promoted an image of a more spiritual and simpler Church.

For centuries, the Lollards, the Wycliffites, the Albigensians and the Cathars had made these heretical assertions or versions of them. But they had never gained traction in Christendom. Things had now changed. Temporal rulers saw in the heresies the path to power, and the idea of Christendom did not long survive the medieval era.

All of these seemingly disparate threads were present in the first years of the 1500s, but they lacked any kind of unifying figure or catalyst. Indeed, had time been granted, the currents of reform building in the Church might have achieved great things. There was in Germany, however, the Augustinian monk, Father Martin Luther, who changed the world with the release of his “95 Theses” to his superiors Oct. 31, 1517. The tradition that he marched to the doors of the Castle Church and nailed the theses upon them for all to see is considered apocryphal.

Finally excommunicated by Pope Leo X through the bull Exsurge Domine June 15, 1520, Luther gave his answer to Rome the following December. A crowd of students and supporters gathered outside the city gates of Wittenberg and gave cheers as Luther tossed into a bonfire copies of the papal bull and of the Code of Canon Law.

In January 1521, Pope Leo imposed a formal excommunication upon the heretical monk. The break had taken place, bringing with it the demise of the unity of Christendom.

The traditional medieval form of justice would have demanded that Luther be arrested by secular authorities and brought to trial as a heretic. Now, in a changed world, Luther was left untouched. Instead of a trial, he was called to appear before the German Diet, a gathering of the devout Emperor Charles V, his court and the princes of the empire, April 18, 1521.

When asked to recant his writings, Luther refused. The emperor had the means to burn Luther at the stake, like Jan Hus before him. The political will, however, was not there. The princes were reluctant, given the emotional support for Luther in their lands, and Charles was thus forced to move slowly, lest he risk civil war. The delay proved crucial for Luther, who was spirited away from harm’s reach by the sympathetic German nobleman and imperial elector Frederick III of Saxony.

Luther may have been removed from the scene (many thought he was dead or executed), but the assembly proceeded with its consideration of the controversy. In May 1521, it issued the Edict of Worms, by which Luther was declared an outlaw and his writings proscribed. Sides were already forming, however, and Frederick III simply chose to ignore the edict while elsewhere far more extreme pro-Lutheran measures were being adopted.

In state after state and especially in the imperial cities, Lutheranism became the state church.

By the time of the Diet of Speyer in 1526, Germany was broken into territories of religious domination in which either Catholicism or Lutheranism was followed by the majority of the inhabitants.

Broadly speaking, Germany’s north fell within the Lutheran sphere, while the south remained Catholic. Across the map were pockets where minorities felt both oppressed and in chronic danger of suppression. Tensions were high, and the sudden dislocating nature of the Reformation’s onset brought violence, unrest and finally protracted bloodshed.

Emperor Charles tried over the next years to find both political and military solutions to the crisis, but by 1555, he surrendered to the hard reality that Protestantism was too deeply entrenched and the princes too determined to protect their independence. Bargaining finally culminated in the Peace of Augsburg. It affirmed the religious division of the empire, acknowledged the de facto existence of Lutheranism, required any Church official who might become Protestant to give up his office before doing so, and supposedly guaranteed the peaceful coexistence between the faiths in the imperial cities.

Augsburg also granted to the princes the exclusive privilege of deciding for themselves what religion was to be followed by their subjects, a settlement expressed in the famous Latin formula cuius regio eius religio (“the religion of the ruler is the religion of the state”). By then, too, bitter divisions had emerged among the reformers themselves.

A compromise that ended briefly decades of bitter hostility, the Peace of Augsburg was far from a final structure for peace in the empire. Its deficiencies were the roots of more anguish, the terrible Thirty Years’ War (1618-1648) that destroyed whole parts of Europe, especially Germany. Christendom was severed, and unity has been elusive ever since.

Matthew Bunson is a

Register senior editor.