In this article, we advance a cultural sociological approach to religious change that foregrounds the role of symbolic pollution and shifting religious imaginaries. Leveraging interviews with 50 Anglo-Canadian Millennials who identify as spiritual but not religious, and ethnographic research at three field sites, we sketch a religious imaginary comprising four discourses of “religion.” According to our informants, “religion” is (1) anti-modern; (2) conservative; (3) American; and (4) colonial. Next, we draw from a combination of modern intellectual history and social histories of twentieth-century Canada to trace each of these discourses genealogically, thereby elucidating how “religion” became symbolically polluted for a large cohort of Canadian Millennials. We conclude with a discussion of the implications our account holds for secularization theory and the study of religious change more broadly.