On the eve of the Protestant Reformation, humanist scholar Erasmus of Rotterdam published a work of satire that set off an earthquake beneath the religious establishment of medieval Europe. His book, “The Praise of Folly,” published in Paris in 1512, was a masterful critique of the arrogance and pretension that characterized the religion of his day. Half a millennium later, it still speaks powerfully as an appeal for spiritual renewal.

The book takes the form of a declamation: a lengthy discourse delivered by a goddess, Folly, who praises herself by pointing out the paradoxes, contradictions and self-deceptions that clutter everyday life, especially the lives of priests and theologians. “They are so blessed by their Self-love,” she says, “as to be fully persuaded that they themselves dwell in the third heaven, looking down from high above on all other mortals, as if they were earth-creeping vermin almost worthy of their pity.”

A former priest himself, Erasmus bristled at the arcane “scholastic” theology that dominated the Catholic medieval schools. Historian Paul Johnson recounts a 1493 debate at the University of Louvain, where Erasmus spent time in study, in which professors argued about the mechanics of prayer. Do four five-minute prayers on consecutive days stand a better chance of being answered than one 20-minute prayer? Is a prayer of 10 minutes, said on behalf of 10 people, as efficacious as 10 one-minute prayers? Writes Johnson: “The debate lasted two months longer than it took Columbus to sail to America in the previous year.”

Speculative theology was a recipe for spiritual pride. It seemed to be the hallmark of church elites, who typically wore elaborate headgear in public to underscore their status as philosophers and theologians. “Don’t be surprised when you see them at public disputations with their heads so carefully wrapped up in swaths of cloth,” warns Folly, “for otherwise they would clearly explode.”

Erasmus also spent time in war-torn Italy, where popes and princes collided — and colluded — over struggles for wealth and influence. He was appalled by the culture of violence, aggravated by the intrigues of the Borgia popes. And he denounced the rhetorical abuse of the Bible to justify the wars of aggression. “Thus this interpreter of the divine mind musters the apostles fully equipped with spears, slings, siege-machines, and cannons,” he complains, “to preach Christ crucified.”

It is sometimes argued that Erasmus had little use for doctrine or church sacraments, and that his humanistic learning inclined him toward skepticism. Yet, as in his other works, “The Praise of Folly” laments the decay of vital Christianity. Legalistic religion, he insists, had failed to transform the human heart. The problem was not sectarian zeal. The problem was the decline of genuine, heartfelt faith.

“You honor a statue of Christ in wood or stone and adorned with colors,” writes Erasmus. “You would do better to honor the image of his mind, which through the Holy Spirit is expressed in the gospels.” This was the foundation for his program of church reform, what he called “the philosophy of Christ.” By it Erasmus meant the moral life of Jesus, intended to be replicated by his followers in every arena of human experience.

The neglect of the spiritual intent of the teachings of Jesus, according to Erasmus, gave a free hand to militant religion: its obsession with doctrine, its culture of suspicion, inflammatory rhetoric, accusations of heresy, and the use of force to silence dissent. The church of the martyrs had become a violent, persecuting church. Thus Erasmus repeatedly implored his readers: “Let us always keep before our eyes the gentleness of Him who, although He alone was free from all error, nevertheless did not extinguish the smoking flax, nor crush the bruised reed.”

As a faithful Catholic, Erasmus drew deeply on his knowledge of Scripture, which he believed was the gateway to spiritual renewal. He sought to have the Bible “translated into all languages” and “published as openly as possible.” As a humanist scholar, Erasmus used the tools of reason and rhetoric to their fullest effect. Like no one before him, he lampooned the stultifying and corrupting power of religious belief gone wrong.

Condemned by the Catholic Inquisition, “The Praise of Folly” nonetheless became an international bestseller. In its assault on divisive and militant religion, it ranks as one of the more subversive works in the history of the Church. “How much more Christian it would be to put aside all conflict,” writes Erasmus, “and bring forward with good spirit whatever is of advantage for the common good.”

In our own age of religious strife and intolerance, it is a message that can hardly be preached too often.

Joseph Loconte, PhD, is an associate professor of history at the King’s College in New York City and the author of ‘The Searchers: A Quest for Faith in the Valley of Doubt’ (Thomas Nelson, 2012).