Given the rise of juridical pluralism and the crisis of liberal constitutional States, the question of the democratic protection has recently regained importance. The present essay focuses on a limited and still unexplored aspect of the protection of democracy: the handling of religious extremist movements and their role as anti-systemic forces. A pivotal support comes from the German constitutional experience: German authorities, in the last years, have taken measures to mark the limits of the freedom of religious association. The bans affected, in particular, a few Islamist movements that tried to undermine the fundamental values of the democratic constitutional State. The essay suggests also directions for further researches on militant democracy as possible link between multicultural politics and constitutional identity.