Faith is not a thought, although thinking follows it; it is not a feeling, though the feeling of comfort emerges from it; neither is faith a virtue nor a moral act. Faith is not glory; it gives no power in the world, it guarantees no success or relief from suffering—indeed suffering increases with faith. What faith does, however, is give unshakeable certainty, the very kind that human works fruitlessly seek, since they place trust in something other than Christ’s promise of the forgiveness of sins. All else in life fails to bring peace or release from anxiety and uncertainty because everything beside Christ’s promise is in the process of being destroyed by God.
From Steven D. Paulson, Lutheran Theology, p. 132.