Sigmund Freud (1856-1939) published this essay in 1927, which is considered the most significant contribution of the founder of psychoanalysis to the topic of religion. In it, Freud interprets religion as an infantile reaction to the human experience of being threatened by the world, from which the longing for a protective father arises. Religion fulfills this desire, but only in the form of a fantasy; thus, it is merely an illusion. As enlightenment and science progress, this illusion increasingly dissolves, leading to the decline of religious belief.