While the question 'Is faith reasonable?' has continually occupied philosophers and theologians, little attention has been paid to the concept of faith itself. The Act of Faith remedies this neglect by looking at what it means for a person of Christian faith to believe. Eric Springsted here contrasts modern views of faith with the Christian tradition running from Augustine through Aquinas and Calvin. Drawing on the work of contemporary thinkers like John Henry Newman and Simone Weil, Springsted shows how the 'inner act' of faith is ultimately a radical willingness to be open to God. He also argues that the faithful self is one that learns and develops a conscience within a community guided by the morally formative activities of interaction, teaching, and sacramental practice.