This paper investigates regional variations in the institutional arrangements governing state-religion relations within German federal states and examines whether these differences still constitute a coherent system of secularism. Contemporary scholarship conceptualizes secularism primarily as the mode through which religious freedom is implemented, while some scholars also emphasize its potential to foster civic inclusion. Germany is commonly treated as a uniform case and classified under the model of cooperative separation between state and religion. Yet significant sociodemographic disparities exist among the federal states - both regarding the salience of Christianity and the presence of Muslim communities - since immigration from predominantly Muslim countries has occurred unevenly across regions. Notably, eastern Germany ranks among the most secularized areas worldwide, whereas other regions continue to identify more strongly with their Christian heritage. Furthermore, considerable variation can be observed in legal frameworks - for example between state constitutions and the Basic Law - in how religion, particularly Christianity, is articulated institutionally. Differences also emerge concerning the expansion or restriction of denominational religious education. This study conducts a comparative analysis of selected federal states to map these legal and institutional configurations and assess whether they uniformly reflect Germany's cooperative separation model or exhibit substantive deviations. The paper concludes by discussing the normative implications such divergences may have for religious communities and broader societal cohesion.