If they are to take part in the public debate of a democratic society, faith communities require some sort of reasoned self-understanding to regulate the process of their self-alteration by reference to their internal norms. While this dynamic self-understanding cannot be provided by merely descriptive studies of religion, the Christian experience offers an example of how this need can be met by the practices and institutions of theology (or its functional equivalents in other traditions). The multidimensional vocation of Christian theology – which is here claimed to be at once scientific and ecclesial, missionary and civic – allows indeed Christian communities to take part in public debate by drawing from their own history and canonical literature the resources they need for their relentless critical self-reinvention. Marc Boss suggests that a democratic state should encourage and support discursive practices of a similar kind in all moral communities it houses, whether the good they pursue is conceived in religious, nonreligious or antireligious terms.