Desiderius Erasmus of Rotterdam, the leading figure of the Northern Renaissance, is widely considered the greatest of early humanists. Five hundred years ago, he faced a populist uprising led by a powerful provocateur, Martin Luther, that resulted in divisions no less explosive than those we see in America and Europe today.

Between 1500 and 1515, Erasmus produced a small library of tracts, textbooks, essays, and dialogues that together offered a blueprint for a new Europe. The old Europe had been dominated by the Roman Church. It emphasized hierarchy, authority, tradition, and the performance of rituals like confession and taking communion. But a new order was emerging, marked by spreading literacy, expanding trade, growing cities, the birth of printing, and the rise of a new middle class intent on becoming not only prosperous but learned, too.

Erasmus became the most articulate spokesman for this class. Moving from city to city in search of good libraries, fine wine, sparkling conversation, and skilled printers, he produced a new “design for living” based on the principles of tolerance, pluralism, concord, and virtuous conduct. In his 1515 essay Dulce bellum inexpertis (“War is sweet only to those who have not experienced it”), he denounced the ceaseless wars waged by rash princes. In The Education of a Christian Prince (1516), he offered a guide to good governance, urging sovereigns to pursue not their own interests but those of the people. In The Praise of Folly (1511), he mocked the pretensions and delusions of kings and courtiers, popes and theologians—part of his campaign to discredit the ruling class and open the way for renewal.

At the heart of Erasmus’s program was his revision of the New Testament. To reform Christendom, he felt, the text on which it was based had to be purified. This was the Vulgate, the Latin translation of the Bible. For a thousand years, this document had served as the scriptural foundation of the Roman Church. Many of its doctrines and institutions were based on specific words and phrases in the Vulgate. Yet a close inspection of the text raised many questions about its sacred status. It was marred by spelling mistakes, grammatical errors, clumsy constructions, and scribal blunders.

In 1500, Erasmus set out to learn Greek so that he could read the Gospels and Epistles in the language in which they had originally been written. (After the fall of Rome, knowledge of Greek had more or less disappeared from the Latin West.) He also began hunting down old manuscripts of the Greek New Testament; by comparing and collating them, he hoped to conjecture what their authors truly meant.

In early 1516, after months of exhausting writing, editing, and proofreading in the print shop of Johann Froben in Basel, Switzerland, the work was done. In addition to providing a revised Latin translation of the New Testament and a parallel Greek text (the first ever printed), Erasmus offered hundreds of annotations explaining the changes he had made. In them, he argued for a new way of reading the Bible—not as a collection of miracles, prophecies, and supernatural acts, but as the story of a transcendent being whose simplicity, humility, and compassion could encourage readers to change their ways and follow a more pious path.

The publication of Erasmus’s revised New Testament was a milestone in biblical studies. It gave scholars the tools to read the Bible as a document that, while divinely inspired, was a human product that could be deconstructed and edited in the same manner as a text by Livy or Seneca. As copies began circulating, the magnitude of Erasmus’s achievement was immediately recognized. Not since Cicero had an intellectual figure so dominated Western discourse as Erasmus did in that enchanted spring of 1516. “Everywhere in all Christendom your fame is spreading,” wrote John Watson, a rector in England with whom he was friendly. “By the unanimous verdict of all scholars, you are voted the best scholar of them all, and the most learned in both Greek and Latin.”

The term “Erasmian” came into use to describe those who shared his vision. But those Erasmians represented only a small sliver of society. Erasmus wrote exclusively in Latin, for the highly educated, Latin-speaking elite. Dazzled by his readings in ancient Greek, Erasmus began promoting knowledge of that language as no less essential than Latin. “Almost everything worth learning is set forth in these two languages,” he wrote in one of his many educational texts. In these, Erasmus proposed a new curriculum for Europe, with instruction in Latin and Greek at its core.

Knowledge of geography, history, astronomy, and nature was all to be imparted through readings in the classical authors specified by Erasmus. His educational program was, in short, highly elitist, seeking not to prepare ordinary citizens for a productive life but to train an aristocracy of culture and taste that could guide the rest of society. This curriculum became the basis for upper-class schooling in Europe until well into the nineteenth century; through it, knowledge of the classical canon would become a ruthlessly clear indicator of class.

In his own day, Erasmus mocked all who mangled grammar and lacked Greek. “Barbarian” was his favorite term of abuse, directed at medieval schoolmasters, scholastic theologians, and others who were rhetorically impaired. He and his fellow humanists gilded their letters with citations from classical writers to signal their membership in the fraternity of learning. As for vernacular tongues, the use of which was spreading across Europe, Erasmus dismissed them as vulgar.

“It is important for scholars to confine themselves to those languages that have almost exclusively been used in learned writing,” he declared. “The reason is that they do not depend for their guarantee on ordinary people. The people are poor custodians of quality.” In short, Erasmus—that champion of a common humanity—was a world-class snob.

Around the same time that the Erasmians were celebrating the dawn of a new enlightened era, a very different movement was gathering in support of Martin Luther. An Augustinian friar then in his early thirties, Luther had developed his own, unique gospel, founded on the principle of faith. Man, he thought, can win divine grace not through doing good works, as the Latin Church taught, but through belief in Christ. No matter how sincerely one confessed, no matter how many alms one gave, without faith in the Savior, he reasoned, no one can be saved. When Luther made this “discovery,” in around 1515, he felt that he had become “altogether born again and had entered paradise itself through open gates.”

With this new conviction, Luther became disturbed by the Church’s use of indulgences. These dispensations, by remitting the penalties imposed on sinners for their transgressions, reduced the amount of time they had to spend in purgatory before being admitted to heaven. In return, the Church expected a financial contribution. To Luther, this seemed to turn repentance into a form of barter. In protest, he prepared (in Latin) a set of theses for debate that challenged the pope’s authority to grant indulgences. On October 31, 1517, he posted them on the door of the Castle Church in Wittenberg (though historians now question whether he physically affixed them to the door).

Soon appearing in print (in both Latin and a German translation), the Ninety-Five Theses quickly spread across Germany. Indulgences were but one of many instruments Rome used to extract money from the German people, and Luther’s protest fanned their resentment. Initially, the Vatican ignored him, assuming the matter would blow over, but the friar—driven, blunt, fearless—spoke out ever more forcefully against what he considered Rome’s arrogance, greed, and corruption. In addition to writing thick theological tracts in Latin, he produced sharp popular pamphlets in German. In them, Luther used an earthy, folksy, and sometimes scatological idiom that helped carry his ideas far beyond the educated elites who were drawn to Erasmus and his high-minded program of social and scriptural renewal.

In his famous 1520 tract To the Christian Nobility of the German Nation, Luther (writing in the vernacular) offered his own reform program. Along with a piercing attack on Rome’s oppressive practices, he proposed twenty-seven measures to protect both the souls and pocketbooks of the German people. He also rejected the idea that the clergy make up a separate spiritual class superior to the laity. All Christians, he declared, are priests of equal standing, free to read and interpret the Bible for themselves. Such attacks on privileged elites endeared him to Herr Omnes, “Mr. Everyman.”

Because of such defiance, Luther was ordered to appear before Charles V, the Holy Roman Emperor, at the Diet of Worms in April 1521. Refusing to recant his writings, Luther made his famous stand on behalf of his conscience as a Christian. For that, he could have been seized on the spot and burned as a heretic, but with the German people mobilizing behind him, any effort to arrest him would have caused a riot. So Luther was able to leave Worms, resume his writing, and set in motion the Reformation.

Initially, Luther admired Erasmus and his efforts to reform the Church, but over time Luther’s inflammatory language and his stress on faith instead of good works led to a painful separation. The flashpoint was the debate over whether man has free will. In dueling tracts, Erasmus suggested that he does, while Luther vehemently objected; after that, the two men considered each other mortal enemies.

Beyond that immediate matter of dispute, however, their conflict represented the clash of two contrasting world views—those of the Renaissance and the Reformation. Erasmus was an internationalist who sought to establish a borderless Christian union; Luther was a nationalist who appealed to the patriotism of the German people. Where Erasmus wrote exclusively in Latin, Luther often used the vernacular, the better to reach the common man. Erasmus wanted to educate a learned caste; Luther, to evangelize the masses. For years, they waged a battle of ideas, with each seeking to win over Europe to his side, but Erasmus’s reformist and universalist creed could not match Luther’s more emotional and nationalistic one; even some of Erasmus’s closest disciples eventually defected to Luther’s camp. Erasmus became an increasingly marginal figure, scorned by both Catholics, for being too critical of the Church, and Lutherans, for being too timid. In a turbulent and polarized age, he was the archetypal reasonable liberal.

Even as his reputation faded, Erasmus worked to complete his blueprint for Europe. In The Complaint of Peace, he decried the nationalist enmities that were splitting the continent. “The English are hostile to the French, for no other reason than that they are French,” he wrote. “The Scots are disliked by the British, solely for being Scots. Germans don’t agree with French, Spaniards don’t agree with either. What perversity—for the mere name of a place to divide people when there is so much which could bring them together!”

Disturbed by the growing bitterness between Catholics and Protestants, Erasmus called on Christians to put aside their private hatreds and bitter quarrels, and instead nurture a spirit of accommodation so that peace could reign. On Mending the Peace of the Church, as he titled the tract, was a resonant appeal for religious tolerance—a formative document in the development of that tradition.

As his end approached, Erasmus sought to warn his fellow Christians of the catastrophe he saw looming—in vain. After his death, in 1536, Europe descended into a century of religious-fueled violence, culminating in the Thirty Years’ War (1618–1648)—the continent’s most destructive conflict before World War I. Erasmus’s ideas about tolerance, peace, and clemency were ruthlessly suppressed. Both Catholics and Protestants dismissed him as a weak, vacillating man who lacked ardor and conviction, and whose commitment to an irenic form of Christianity founded on the Gospels was as objectionable as it was obsolete.

Yet Erasmus’s vision of a united Europe in which people of differing beliefs share a common citizenship would live on, providing an intellectual haven amid the eruptions of nationalism, xenophobia, racism, and nihilistic violence that periodically ravaged the continent. Despite its snobbism and elitism, Erasmian humanism offered an alternative to the apocalypse.

Luther underwent his own reverses. When, in 1524–1525, the German peasants—inspired in part by his writings—rose up against their spiritual and secular overlords, Luther, fearing anarchy, denounced them as mad dogs who deserved to be stabbed, smitten, and slayed. With that, the common man turned irrevocably against Luther. A wrenching dispute over whether the body of Christ is present in the bread of communion led to an irreparable breach with the Swiss branch of the Reformation. And Luther’s uncompromising insistence on the rectitude of his own beliefs alienated many moderates, and not just Catholic ones.

By the time of his death, in 1546, Luther had become an isolated reactionary, his work eclipsed by a younger and more dynamic reformer, John Calvin. Even so, Luther would go down in history as the founder of Protestantism, the man who broke the spiritual stranglehold of the Roman Church. Luther’s brand of Bible-based ardor founded on pure faith would exercise a profound influence on Western culture, not least in America.