The Concept of Anxiety
All of Kierkegaard's books have either a preface, dedication, or prayer at the beginning. This book includes a lengthy introduction. "The Concept of Anxiety" was published on exactly the same date as "Prefaces", June 17, 1844. Both books deal with Hegel’s idea of mediation. Mediation is a common thread throughout Kierkegaard’s works. His work up to this point was to show that faith was being mediated by knowledge. Here he takes up the questions of sin and guilt.
Johann Christian August Heinroth
Heinroth regarded sin as a cause of mental illness. His description of sin came from a 19th-century Protestant standpoint, and was also derived from an accepted European code of ethics and morality. His definition of sin wasn't based on a singular event, but rather as a period of several years of an individual striving towards earthly, bodily satisfaction. From a philosophical point of view, Heinroth espoused the teachings of Johann Gottfried Herder (1744–1803).