This book takes seriously the proposition that existentialism is a lived philosophy. Philosophy is personal and Kierkegaard's writings deal with the development of the person in their aesthetic, ethical and religious dimensions. The book argues that authentic faith actually entails faith. The existential believer has this faith whereas the religious believer does not. The subjectively reflective existential believer recognizes that a leap of faith is needed; anything else, is just historical, speculative knowledge. With original insight, the book shows that Kierkegaard's example of Abraham as a Knight of Faith is incorrect. Unamuno's faith of the "paradoxical believer" is given as a strong alternative to those who find that Kierkegaard's existential faith is not a possibility.