In this article, I explore how nations without states, or ‘stateless nations’ respond to new forms of religious diversity. Drawing on the cases of Quebec and Catalonia, I do so by tracing the historical emergence of the cultural narratives that are mobilized to support institutional responses to diversity and the way they bear on contemporary controversies. The article builds on recent research and theorizations of religious diversity and secularism, which it expands and specifies by spelling out how pre‐existing cultural anxieties stemming from fears over national survival are stored in collective memories and, if successfully mobilized, feed into responses to migration‐driven religious diversification. I show that while Quebec and Catalonia were in many ways similarly positioned before the onset of powerful modernization processes and the resurgence of nationalism from the 1960s onwards, their responses to religious diversity differ dramatically.