In post-war Britain, the decline of Christianity's social hegemony and the rise of culturally diverse urban contexts prompted new forms of community-making. Based on historical and architectural analysis, this paper shows how Christian communities produced multifunctional, ecumenical, and adaptive spaces - ranging from new parish halls and purpose-built interconfessional centres to the repurposing of historic churches - that enabled shared worship, social services, and civic engagement. It argues that these spatial strategies anticipated contemporary debates on relational, inclusive, and negotiable religious space, revealing how Christian communities negotiated authority, agency, and collective life across urban and historical contexts.