This article was originally posted at The Times.

Next year marks the 500th anniversary of Martin Luther’s challenge to the Catholic Church that launched the Protestant Reformation. However, it was in 1516 that a brilliant scholar and reformer — a Catholic humanist — cleared a path for the spiritual revolution that would shatter the unity of Christendom.

Desiderius Erasmus, the foremost disseminator of classical culture in Europe, published his greatest literary achievement 500 years ago: an edition of the Greek text of the New Testament, the first of its kind in print, with a parallel Latin translation and commentary. Erasmus was appalled by the moral turpitude of the church: the warrior popes, heresy trials, priestly concubines and lust for wealth and worldly power. Dogma had displaced authentic piety. A return to the original text of Scripture, he believed, would make possible “the restoration and rebuilding of the Christian religion”.

Erasmus’s new text, based on a study of original Greek manuscripts, casts doubt on the Latin (Vulgate) translation of the Bible, first made by Jerome in AD382 and endorsed as authoritative by the Church. Erasmus translated a statement from Jesus in Matthew iv, 17, for example, as “repent, for the kingdom of Heaven is at hand”. This was at odds with the Latin rendering “do penance”, cited by the Church to justify its elaborate system of punishments as payment for sin.

The work set off a storm of controversy. One critic warned that if the Vulgate was in error, “the authority of theologians would be shaken, and indeed the Catholic Church would collapse from the foundations”.

Yet Erasmus saw no conflict between the aims of the Christian educator and the tools of the humanist scholar, namely the study of ancient texts in their original grammatical and historical setting. His Greek translation was the opening barrage in a battle for the right of biblical criticism.

Martin Luther received the new translation in Wittenberg while he was lecturing on the book of Romans. From that moment, according to the biographer Roland Bainton, the Erasmus text “became his working tool”. Topping the list of Luther’s 95 indictments, hammered to the door of All Saints’ Church on October 31, was an assault on penitential theology. “When our Lord and Master, Jesus Christ, said ‘repent’, he called for the entire life of believers to be one of repentance,” he declared. “The word cannot be properly understood as referring to the sacrament of penance . . . as administered by the clergy.”

Perhaps the most subversive quality of Erasmus’s humanism was his attempt to recover the moral life of Jesus — a life of humility, compassion and love for one’s enemies. “What else is this philosophy of Christ, which he himself calls being born again,” he wrote in the preface to his Greek New Testament, “but the renewal of human nature well formed?” He wanted the Bible “translated into all languages” and made accessible to ordinary believers. “I would that even the lowliest woman read the Gospels and the Pauline Epistles,” he said.

On the eve of the Reformation, Erasmus — a counsellor to princes and cardinals alike — was at the height of his influence and fame. Luther was emboldened by his example. Like Erasmus, Luther believed that the Church had exchanged a message of grace for a mechanical and legalistic religion.

Thus Luther produced his own translation of the Bible into German. It was a watershed event: with the increasing availability of the printing press, there was no stopping him.

Although Luther ultimately broke with Erasmus over his loyalty to the Catholic Church, Erasmus never publicly condemned him. Instead, Erasmus criticised church leaders as “a pestilence to Christendom” for attacking Luther’s Ninety-five Theses and his campaign for reform. “If, as appears from the wonderful success of Luther’s cause, God wills this, and He has perhaps judged such a drastic surgeon as Luther necessary for the corruption of these times,” he wrote, “then it is not my business to withstand him.”

Once Erasmus helped to set the surgeon loose, the west would undergo both trauma and recovery—a Reformation from which there was no retreat.

Joseph Loconte is an associate professor of history at the King’s College in New York City and the author of A Hobbit, a Wardrobe, and a Great War: How J.R.R. Tolkien and C.S. Lewis Rediscovered Faith, Friendship, and Heroism in the Cataclysm of 1914-1918.