Understanding the electoral success of right-wing populist parties has sparked the interest of many scholars. One factor receiving less attention in these debates is the role of religious affiliation as a cultural marker of allegedly dangerous out-groups. Right-wing populists often portray themselves as defenders of a Christian Occident that is allegedly under threat by an invasion of Muslims. We argue, in accordance with the culturalbacklash thesis, that the mobilization of right-wing populists would not have been possible without the widespread perception of Islam and Muslims as a threat. To test this assumption, we analyzed data from the European Social Survey (2014). Our results show that support for a ban against Muslims increases the likelihood of voting for right-wing populist parties, and the percentage of Muslims in the total population has no moderating effect. The individual linkage between anti-Muslim prejudices and the support of right-wing populist parties is a pan-European phenomenon. Interestingly, right-wing populists profit from anti-Muslim prejudices in places where few Muslims live. Thus, the absence of Muslims seems to favor a social climate in which anti-Muslim sentiments prevail. "Islamophobia without Muslims" offers right-wing populists a political window of opportunity to join government coalitions or even to win elections.