Measuring religious attitudes: reliability and validity of the German version of the Systems of Belief Inventory (SBI-15R-D) in a representative sample

There is a lack of economical and reliable instruments to measure religious attitudes in the German language. Therefore, we analyzed a German version of an originally-American, 15-item questionnaire. The German version of the two-scale Systems of Belief Inventory (SBI-15R) by Holland et al. (1998) was validated in a representative sample (N=1,967). The overall scale and the two subscales were shown to be highly reliable (Cronbach's alpha > 0.94). They discriminate between members and non-members of religious bodies (effect size > 1.14), correlate in the expected direction with respondents’ self-description as ‘religious’ (r > 0.62) and with the importance of religion and/or faith in childhood (r > 0.61). Unlike the original, we found a unifactorial solution for the German version; hence, the overall score for the assessment of general religiosity appears sufficient. Based on these findings, SBI-15R-D represents an economical, practical and reliable instrument for assessing religiosity in persons of German language and cultural background.