Kierkegaard’s writings are a mosaic of explorations of such spiritual excellences as faith, love, hope, patience, compassion, forgiveness, and bold confidence, explorations designed to “build up” the reader in these traits. The treatment of faith in The Sickness unto Death follows the classical pattern of virtue as an actualization of a creature’s potentiality. Faith is that state in which people realize the human telos; it is the completion of human nature. In Kierkegaard’s thought, all the other virtues presuppose the virtue of faith. But The Sickness unto Death also presents sin, the psychological condition that underlies wrongdoing, as deep and pervasive in a way that rules out some of the classical features of human virtues, for example that they are realizable perfections developed by habituation, and that virtue has not been achieved in a person who still has to struggle against vicious impulses. The features of Christian virtues that make them compatible with sin are that they depend on grace, that their development is subject to an “inverse dialectic,” that the conceptual grammar of many of the virtues makes reference to sin and sinfulness and more broadly accountability to God, and that the Christian virtues are not, at least in this life, perfections.