Using data from the American National Election Studies, Poole-Rosenthal DW-Nominate scores, and data on the religious affiliations of members of the United States House of Representatives, I show that religion has important independent effects on the evaluation of candidates' ideologies. The results suggest that candidates affiliated with evangelical Christianity will tend to be seen as more conservative than ideologically similar candidates from mainline Protestant denominations. Jewish candidates, in contrast, will tend to be seen as more liberal than ideologically similar mainline Protestants. Additionally, the use of religion-based stereotypes varies with frequency of church attendance. These findings attest to the external validity of recent experiment-based research on religion-based political stereotypes. The approach employed here also allows for the estimation of the magnitude of the effects of such stereotypes. The results shed light on both the importance of religion in election campaigns and the factors that influence perceptions of candidates' ideologies more generally.