Prior research found that Christian nationalism was strongly associated with voting for Trump in the 2016 U.S. presidential election. However, the effects of Christian nationalism may depend on voters’ religiosity. Using national data, we assess whether the association between Christian nationalism and Trump support differed for churchgoers and nonchurchgoers and find that Christian nationalism is not significantly associated with Trump support among churchgoing voters. Instead, Christian nationalism is only significantly associated with Trump support among unchurched voters. These results suggest that while religious sentiments remain key correlates of political attitudes and behavior in the United States, these ties may have less to do with embeddedness in traditional religious organizations and more to do with the ways people use religious narratives in everyday life to construct and defend symbolic boundaries. At a time when fewer Americans attend religious services, religious narratives about Christian nationhood may have their strongest political effects when, and perhaps because, they are detached from religious institutions.