This article explores populist-oriented far right and islamist discourse through a relational lens to examine how the category of ‘the’ people, specifically the ummah, is co-constituted. In focusing on the islamist category of ‘the’ ummah, the article examines how far right and islamist discourses work together to co-construct an antagonistic frontier. Rather than categorising distinct party families, a relational lens is employed to render visible how both islamist and far right discourses invest in an antagonistic ‘ummah’, or Muslim collective. Through a case study of far right (Party for Freedom) and islamist (Hizb ut-Tahrir) discourses that aim towards separating the Muslim from the secular and liberal Self/Other, the article examines the mutual grounding of an antagonistic frontier. Adhering to the primacy of antagonism in political identification, the article demonstrates a populist conception of ‘the’ ummah is activated and mobilised by both nationalist and islamist forms of articulation. In doing so, the article contributes to the conception and empirical discussion on prevalent forms of radical (and extremist) politics.