To be struck by grace does not mean that we are simply making progress in our moral self-control, in our fight against special faults, and in our relationships to others. Moral progess may be a fruit of grace, but it is not grace itself.
Grace strikes us when we are in great pain and restlessness. It strikes us when we walk through the dark valley of a meaningless and empty life... grace strikes us when our disgust for our own being, our indifference, our weakness, our hostility, and our lack of direction and composure have become intolerable to us.
Sometimes at that moment a wave of light breaks into our darkness and it is as though a voice were saying, "You are accepted. You are accepted by that which is greater than you... Do not seek for anything; do not perform anything; do not intend anything. Simply accept the fact that you are accepted."
If that happens to us, we experience grace. After such an experience we may not be better than before, and we may not believe more than before. But everything is transformed.
- Paul Tillich "The Shaking of the Foundations"