What is more, if they did good works for the sake of obtaining the Kingdom, they would never obtain it, but would rather belong among the ungodly who with an evil and mercenary eye “seek their own” even in God. But the children of God do good with a will that is disinterested, not seeking any reward, but only the glory and will of God, and being ready to do good even if—an impossible supposition—there were neither a kingdom nor a hell. These things are, I think, sufficiently established by that one saying of Christ’s which I have just quoted from Matthew 25[:34]: “Come, O blessed of my Father, inherit the Kingdom prepared for you from the foundation of the world.” How can they merit that which is already theirs and is prepared for them before they are born? We could more truly say that the Kingdom of God merits us as its possessors rather, and thus place merit where they place reward and reward where they place merit. For the Kingdom is not being prepared, but has been prepared, while the sons of the Kingdom are being prepared, not preparing the Kingdom; that is to say, the Kingdom merits the sons, not the sons the Kingdom. So also hell merits and prepares its children rather than they it, for Christ says: “Depart, you cursed, into the eternal fire prepared for the devil and his angels” [Matt. 25:41].
The Bondage of the Will
Luther’s Works Vol. 33