If, as Erasmus wrote, free will could do nothing good apart from the grace of God then free choice without the grace of God was not free at all, but captive and a slave to evil, since it could not turn itself toward the good. Erasmus always appeared ready to welcome a God who acted as an ideal for such concepts as truth, wisdom, beauty, grace, and freedom. However, when it came to terms for God that placed him above sinners - almighty, immutable, foreknowledge and election - then Erasmus changed his tune, resorting to “matters of grammar and the figurative use of words, which even schoolboys understand...” (Rupp, “Luther and Erasmus,” 144.)

As Klaus Schwarzwaeller wrote, Luther’s work in The Bondage of the Will was concerned about salvation only. Luther asked “radically and exclusively for God alone and his will, i.e. the God for us and the Gospel exclusively. ‘Solus Christus’ is carried almost to the extreme, since ‘all humankind is in need of salvation.’” In the proclamation of the Cross, Luther understood that the law was put to an end, put to death, and in its place Christ was raised from the dead. For Luther, “to will the law and the gospel, to unwill sin and to will death belongs to divine power alone, as Paul says in more than one place.” (Klaus Schwarzwaeller. “Sibboleth,” 1969. 8.)

For Erasmus, “the will always seems to be that neutral gear in an automobile which can be shifted this way and that ‘at will.’ This, Luther insisted, was mere abstraction, a logical fiction. “A will, to be a will, always wills something, either good or evil.” (Forde, “Captivation of the Will,” 71.) Human disaffection with God, assuming choice and neutrality, will always make the error of assuming there is a free will. Luther wrote:

The truth is rather as Christ puts it: ‘He that is not with me is against me’ (Matt. 12.30). He does not say: he that is not with me is not against me either, but in an intermediate position! For if God is in us, Satan is out of us, and then it is present with us to will only good. But if God is not in us, Satan is, and then it is present with us to will only evil. Neither God nor Satan permits there to be in us mere willing in the abstract; but as you rightly said, we have lost our freedom and are forced to serve sin - that is, we will sin and evil, we speak sin and evil, we do sin and evil! (Packer, “Bondage of The Will,” 147.)

Luther understood when the Word of God came it did not offer sinners a choice. When Christ came an eschatological battle took place between God and sinful humanity. As Luther put it, “whenever the word of God comes into the world, sinners grow worse the more they are instructed.” In fact, the preaching of the Gospel only intensified the battle, “hastening the wrath of God, just as the Flood was hastened then, for it not only means that sin is committed but also that grace is despised, as Christ said, ‘When the light comes, men hate the light” (Packer, “Bondage of the Will,” 240-241.)