Shaped by migration, cities are and always have been places of encounter of diverse populations. They thus are spaces of coexistence, conviviality and multiple modi vivendi as well as places of political innovation dealing with societal diversity. Here, we first observe how religion changes (in) societies transformed by migration, secularisation, individualisation and a neoliberal economy. In urban areas, the strongest possible estrangement from religion and the broadest possible religious diversity - from new religious movements and different forms of spiritualty to religious minorities growing through migration - occur side by side. Urban areas are also characterised by a deep ambivalence, as, for many, they are both places of hope and opportunity and sites of conflict and social deprivation. This ambivalence shapes the interactions in and negotiation of urban public spaces.

For social sciences, when studying religion, theology and philosophy, the engagement with these urban laboratories is a promising starting point to further develop our understanding of how religion impacts major transformation processes of contemporary society. For empirical research, cities provide a valuable frame to avoid methodological nationalism and the reproduction of already overcome categories. Political science sees the migratory city as a space where different possibilities of political participation coexist and as a space that provides room for democratic innovation on a local level. Religious studies investigate contemporary religious landscapes in their full range in urban areas. Through the urbanization processes of the 21st century in the context of international migrations, practical theology is reminded of the biblical vision of the "City of God", which is to be built as a "laboratory of God", not least with the help of migrants in all places of the world. Moreover, urbanisation and migration pose new challenges to the Christian churches in Europe.