Why did both Catholics and Protestants become suspicious of Desiderius Erasmus?

Desiderius Erasmus became a target of suspicion for both Catholics and Protestants primarily because he maintained an independent stance during an era of intense religious conflict, refusing to align fully with either side.1

His position alienated both factions for several reasons:

• Catholic Suspicion: Many Catholic theologians viewed Erasmus with hostility because his critical approach to ecclesiastical abuses and his independent study of the New Testament were seen as precursors to the Reformation. His works were eventually placed on the Index expurgatorius, and he was frequently denounced by those who felt his humanistic methods threatened traditional orthodoxy.213
• Protestant Suspicion: While some early reformers admired his work, Erasmus ultimately rejected key Protestant doctrines, such as predestination. His defense of free will in De libero arbitrio led to a direct theological confrontation with Martin Luther, causing many Protestants to label him a traitor to the Gospel.13

Ultimately, Erasmus’s commitment to church unity and his rejection of the "cruel logic" of religious persecution made him a beacon for those valuing liberty over the rigid demands of partisan orthodoxy.13