In the first part, the paper gives an overview of the central notion of freedom in general, especially positive and negative freedom, freedom of will and freedom of action. It comes to the conclusion that in a secular world, the government has no epistemic or deontic authority in questions of religion. In the second part, it shows that the idea of freedom of religion is quite new and that it is not accepted in every culture. There are two cases which exemplify this insight: the trial and damnation of Socrates and the “Compelle intrare” of Augustinus. The last part of the paper presents the origin and development of the concept of freedom of religion in Samuel Pufendorf’s “De habitu religionis christianae ad vitam civilem” and in John Locke’s “Epistula de tolerantia”. Freedom of religion could only evolve in the course of the philosophical and theological interpretation of Christian faith.