On the Freedom of the Will raises a crucial theological question: To what extent, if any, does human merit contribute to salvation? By ascribing a greater role to divine grace and a lesser one to free will and human effort, Erasmus hoped to produce a compromise that would be equally acceptable to both Lutherans and orthodox Catholics. Although he clearly disagreed with Luther in substantial ways, he did not deny that Luther had some valid arguments. In particular, he praised the German reformer’s fundamental belief that Christians must place their entire trust in God and not rely on their own merit for salvation; but he also felt that Luther was wrong to deny completely the soteriological importance of free will.
What disturbed Erasmus most, however, was the virulent, uncompromising nature of Luther’s campaign against the tradition and authority of the Catholic Church. As he stated in his introductory remarks to On the Freedom of the Will, some cures are simply more harmful than the afflictions they seek to remedy. Like Luther, he felt that moral corruption had seriously compromised the integrity of the Catholic Church at all levels, yet he did not believe that open confrontation would contribute to meaningful reform. If there was going to be a debate, he felt it should be conducted with moderation and evangelical mildness.
The debate opposing Erasmus and Luther on free will did not end there, nor did it remain a polite exchange of ideas as Erasmus clearly had hoped. Confident that truth was on their side, the Lutherans and other Protestant groups persisted in their defiance of Catholic authority. In December of 1525, Luther replied to the Dutch humanist’s criticism by publishing his De servo arbitrio (Martin Luther on the Bondage of the Will, 1823). The work was a stark rebuttal of Erasmus’s views on free will, salvation, foreknowledge, the origin of evil, and the authority of the Catholic Church. This prompted Erasmus to reaffirm his critique of Luther doctrine, this time with rancorous venom, in a two-part treatise titled Hyperaspistes (1526-1527; English translation, 1999 and 2000). By that point in time, all hope of reconciliation had vanished.