Religious Affiliation as a Baseline for Religious Diversity in Contemporary Europe: Making Sense of Numbers, Wordings, and Cultural Meanings

This working paper reports on the data and findings of the SNSF-research project “Swiss Metadatabase of Religious Affiliation in Europe (SMRE)”. Eight years ago, the two authors started with the simple, yet irritating observation that the existing data on religious affiliation in various European countries frequently showed substantial differences. The SMRE-project was set up to investigate this situation in more detail and to improve the data quality. The project became funded by the SNSF in 2015 and thus resulted in “big data work” (in the double sense of the word). After years of collecting, comparing, and integrating data from various sources into the newly designed, internetbased SMRE-metadatabase, the working paper presents new statistical estimates on religious affiliation in Europe on a country and EU-level. The numbers given are validated and standardized estimates allowing for comparisons across countries, between two time-periods (2000: 1996-2005, and 2010: 2006-2015). The SMRE covers 50 European and neighbouring Eastern states, as well as the European Union and the Council of Europe as special entities. The SMRE-estimates result from a heuristic model of religion, a working definition of religious affiliation, a transparent and consistent rating procedure and finally a general algorithm for integrating the existing wealth of data into a single statistical data set on religious affiliation in Europe. The SMRE presents estimates in the sense that, to the best of our knowledge, these data are reliable
numeric expressions for the distribution of religious affiliation in Europe, i.e. the (rough) percentage of people who say they belong to one out of eight major European religious, including the category No religious affiliation.

The paper starts with the current state of research, documents the SMRE-approach and its algorithm and reports the substantial results of analysing the SMRE-estimates by means of descriptive and explorative data analysis. Our analysis shows that the religious landscape measured by religious affiliation has become a double-layered structure in Europe. First, the legacies of the different, historically dominant Christian traditions are still shaping today’s religious scene. Path dependencies are clearly at work. Secondly, the 20th century shift towards larger shares of people with no religious affiliation in European countries altered the structure of many, yet not of all countries significantly. In addition, more recent developments of using religion in identity politics are leading to homogenisation in a few countries. As a result, Europe and the European Union show large differences in the degree of religious pluralisation today. In terms of EU member states, their differences in religious affiliation and its changes even tend to separate the old and new member states religiously and culturally. There is a need for more detailed investigations into religious diversity and pluralisation in Europe across countries. The SMRE-estimates on religious affiliation provide a new baseline for such research. All SMRE-data are made available as open research data (www.smre-data.ch).