In the article an attempt is made to deal with the so-called Böckenförde dilemma: "The liberal secular state lives from sources it cannot guarantee itself". The dilemma behind this phrase consists of the following two alternatives: either the liberal state ignores religion and thus runs the danger of loosing its cohesive forces. Or it promotes religion with the risk of loosing its neutrality in religious affairs. First, three traditional models for describing the public role of religion in liberal democratic societies are critically discussed: the civil religion, the Western Occident and the discourse models. Second, the re-affirmation of a positive public role for religion in democratic societies in recent sociology and social philosophy is pointed out. Third, a case is made out for the recognition of a positive freedom, instead of only a negative freedom of religion. In conclusion a number of guidelines for a public theology that gives content to the positive freedom of religion in an adequate way are provided.