Luther does not develop a theology of hope because hope is not the central driver of his mature theology. Central for him is rather faith in the promise of God, which gives rise to hope as well as love. There are two sides to justification that correspond to the now/not-yet character of Luther’s eschatology. On the one hand, we are already righteous through the gift of Christ’s righteousness, which we have in spe but not yet in re. On the other hand, the hope of righteousness strengthens us against sin as we wait for the perfection of our righteousness in heaven. However, in the final analysis, the basis of our hope is not the incipient righteousness which has begun in us (in re) as we gradually grow in holiness and righteousness, but Christ’s own perfect righteousness which he imputes to us through faith (iustitia aliena). For hope can only be rock-solid if it is grounded not on anything within us, but on Christ alone.
The early Luther has a very different view of things because, before 1518, he is still very much under the influence of Augustine, which means that justification is primarily a process that goes on within a person’s heart rather than, as in the later Luther, faith in God’s word of promise that comes to a person from outside and gives what it says. The dominant theological concept in Luther’s early work is the theology of humility, which is predicated on the view that God must first humble you and cause you to despair, before he can raise you up and give you hope. Since here faith is not yet oriented to the promise but defined by humility, it has to remain uncertain, as does hope. In the later Luther, on the other hand, faith gives rise to confidence and hope because it is firmly grounded in God’s word of promise, which is always reliable because God does what he says.
With his faith firmly grounded in Christ, Luther knows that he can weather all the trials and struggles of life; in fact, he can even look forward to death, since for Christians death is but the door to life with God forever. For Luther, Christ is the only hope for a hopeless world. For him, this is not wishful thinking but is rock-solid because it is based on the promise of the crucified and risen Lord. This is also the basis of the Christian hope for eternal life in the presence of the Triune God, together with the renewed creation and all the hosts of heaven.