The traditional cleavages like social class or religion are often reported to have lost explanatory power for the voting decision. Regarding the religious cleavage, the evidence is ambiguous depending on the choice of cases and indicators used. The present study tests the impact of religion for the preference to vote the Christian Democratic Party of Switzerland (CVP) using data from the 2007 and 2011 Swiss national elections. Additional to the inclusion of individual variables, a special focus lies on contextual effects. The estimated hierarchical linear models confirm a prevailing influence of the simple individual factors and the presence of a significant contextual effect. Statistical evidence is also presented for some of the supposed interaction effects between individual and contextual religious variables.