The article provides data that attest to the severity of the European demographic, economic, and political decline, and considers one of its manifestations, the capacity of the secular state to cope with the transformations of the European religious landscape. The secular state has been a European invention, and the decline of Europe has inevitable repercussions for its vitality, in Europe and beyond. In Europe, the weakness of the secular state has been revealed by the diversification of the European religious landscape. A declining Europe is less and less capable of managing diversity using the tools provided by the secular state. Analysis of the different models of secular states implemented in Europe is followed by a reexamination of the issue of the decline of Europe, and of its effect on the reforms that are required to adapt the secular state to the new conditions. The article provides data that attest to the severity of the European demographic, economic, and political decline, and considers one of its manifestations, the capacity of the secular state to cope with the transformations of the European religious landscape. The secular state has been a European invention, and the decline of Europe has inevitable repercussions for its vitality, in Europe and beyond. In Europe, the weakness of the secular state has been revealed by the diversification of the European religious landscape. A declining Europe is less and less capable of managing diversity using the tools provided by the secular state. Analysis of the different models of secular states implemented in Europe is followed by a reexamination of the issue of the decline of Europe, and of its effect on the reforms that are required to adapt the secular state to the new conditions.