Luther on Human Freedom
In 1525 Martin Luther wrote De servo arbitrio (Bondage of the Will) to reply to Erasmus of Rotterdam who wrote A Diatribe or Discourse concerning Free Choice (De libero arbitrio diatribe sire collatio) shortened to De libero arbitrio (Freedom of the Will) a year earlier.
In short, if we are under the god of this world, away from the work and Spirit of the true God, we are held captive to his will, as Paul says to Timothy [II Tim. 2:26], so that we cannot will anything but what he wills. For he is that strong man armed, who guards his own palace in such a way that those whom he possesses are in peace [Luke 11:21], so as to prevent them from stirring up any thought or feeling against him; otherwise, the kingdom of Satan being divided against itself would not stand [Luke 11:18], whereas Christ affirms that it does stand. And this we do readily and willingly, according to the nature of the will, which would not be a will if it were compelled; for compulsion is rather (so to say) “unwill.” But if a Stronger One comes who overcomes him and takes us as His spoil, then through his Spirit we are again slaves and captives-though this is royal freedom-so that we readily will and do what he wills. Thus the human will is placed between the two like a beast of burden. If God rides it, it wills and goes where God wills, as the psalm says: “I am become as a beast [before thee] and I am always with thee” [Ps. 73:22 f.]. If Satan rides it, it wills and goes where Satan wills; nor can it choose to run to either of the two riders or to seek him out, but the riders themselves contend for the possession and control of it.
Luther, Bondage of the Will, from Luther’s Works Vol. 33
Luther compared human’s will with beast of burden, who cannot chooses who rides it – If God rides it then it wills and goes where God wills; if the devil rides it then it wills and goes where he wills. In other words human has no freedom – all his acts are governed by who controls him. Using modern analogy, according to Luther humans are like cars – a car cannot choose its driver and its behaviour depends on who sits behind steering wheel. The denial of human freedom leads to double predestination, i.e. only those that God chooses “to ride” (following Luther’s analogy) will go to heaven while those not chosen will have the devil as rider and end up in hell.
The Catholic Church, on the other hand, teaches we have freedom of will. Yet at the same time we cannot use our free will to will our salvation. God, through His Grace, takes the initiative for our salvation and we, using our freedom, respond to it – we can either decide to accept or to reject His Grace.