Ideological religious nationalism (IRN) is a worldview that advocates the integration of religious beliefs with national policy and laws and the religious moralization of politics. However, the psychological mechanisms, individual differences, and socio-political consequences related to IRN are unclear. Across five studies (NTotal = 1,349), we established construct validity for a novel scale assessing IRN that is adaptable across different contexts. Results showed that stronger IRN relates to distinct psychological motives, domains of religiosity, and views of one’s nation. Results also showed that stronger IRN relates to supporting policies that promote religious-national integration and support of political violence. Lastly, results show that this novel IRN scale can be used across different contexts and has incremental validity beyond similar but distinct measures of religious nationalism. Overall, results showed that IRN can successfully capture people’s integration of their religious beliefs with their views about their nation’s identity.