This study investigates the relationship between religiosity, authoritarianism, and nationalism in Poland in 2023, drawing on theories of religious nationalism and authoritarian personality. Building on the insights from the literature on religious nationalism, moral traditionalism and right-wing authoritarianism, we hypothesize that religiosity positively influences nationalist views, operating indirectly through authoritarian predispositions that channel religious commitments into nationalist attitudes. Nationalism was operationalized as a multidimensional construct encompassing attitudes toward national pride, perceived threats to identity, and resistance to the European Union’s cultural influence. Using data from the 2018, and 2023 waves of POLPAN, 1 a long-running Polish panel survey, we examined both cross-sectional and longitudinal dynamics. Results demonstrate that religiosity exerts a strong direct effect on nationalism, while authoritarianism functions as a mediating orientation that independently reinforces nationalist attitudes. Lagged regression models confirm the temporal stability of nationalism, yet also reveal that religiosity and authoritarianism contribute to its intensification over time. These findings contribute to debates on the intersection of religiosity, authoritarianism, and nationalism, highlighting the enduring relevance of theories of religious nationalism and authoritarian predispositions in contemporary Poland.