In 1516, having worked as a chaplain in the wars, Ulrich Zwingli was appointed parish priest of Einsiedeln, a Swiss pilgrimage church renowned for its Virgin Mary shrine. The new appointment was a milestone in his intellectual and spiritual formation. It was while he was in Einsiedeln that Zwingli came across a copy of Erasmus' Greek New Testament for the first time, an experience that profoundly and enduringly affected him. Erasmus, a prominent Renaissance scholar and church corruption critic, released this book to promote greater, more precise study of the original texts of the Bible. For Zwingli, this find revolutionized his comprehension of faith and Scripture. Before reading Erasmus' New Testament, Zwingli had already been deeply influenced by Renaissance humanism, with its emphasis on reason, skepticism, and return to classical sources of knowledge.

While he appreciated the intellectual discipline of humanism, Zwingli had not yet identified these concepts with his religious faith. Erasmus' translation gave him a new perspective. Through a study of the original Greek manuscripts, Zwingli was convinced of the infallibility and inner coherence of the Bible two beliefs that would be the cornerstone of his future reform movements. Scripture alone, he believed, was the final word on matters of faith, not institutional church tradition or dogma. Motivated by this newfound love for the Word, Zwingli traveled to Basel to meet Erasmus in person. This meeting was pivotal in cementing Zwingli’s dedication to scriptural study and reform. Erasmus, though cautious about breaking from the Catholic Church, encouraged Zwingli’s commitment to biblical literacy and independent thought. Their conversation inspired Zwingli to dig deeper into the Scriptures and begin questioning the practices of the church.

During this period, Zwingli also traveled to Rome. While the city’s architectural and cultural splendor impressed him, his visit revealed the extent of corruption within the Papal court. He witnessed the wealth and opulence of the clergy, which stood in stark contrast to the simplicity and humility that the Gospels preached. This experience further deepened Zwingli’s disillusionment with the church’s worldly ambitions and reinforced his growing belief that the church needed radical spiritual reform.

Zwingli’s time in Einsiedeln was a critical phase in his transformation from a Renaissance humanist to a passionate advocate for scriptural authority. His encounters with Erasmus and his observations in Rome helped lay the foundation for the theological convictions that would guide his future work as a leading figure in the Protestant Reformation.