This text highlights key aspects of the religion/church-state relationship/debate, and related hitherto marginal topics. The contributions make clear that there is no clear blueprint for an optimal relationship between religion/church and state.  Individual states and countries are analysed on the granular level for example, to address mono-religious against poly-religious as well as secular societies.  Among others, chapters address education, migration and politics against religion as well as the effect of LGBTQ+ communities on religion and societies. This collected volume appeals to researchers, and students working in religious studies and political science.