The CERES religious diversity index by country can only be understand as very first and yet limited step towards the development of a more secure methodological rationale. There still remains an urgent need for new empirical methods of operationalisation in order to assess possible consequences of religous pluralisation processes worldwide.
Model for future research
For now, the innovative form of measuring religious diversity as developed in the project Religious Plurality in three European Countries can not be transfered to the religious diversity index by country. The reason for this is simply the lack of suitable data. While these databases divide Christianity into subgroups (Catholic, Protestant, Orthodox), other religions such as Islam and Hinduism appear as solid entities without any inner differentiation. Given these incomplete and less precise data records, the question how processes of vitalisation and/or secularisation effect religions and countries can not be answered on a global level yet.
The following data are needed to generate a more precise future religious diversity index for every single country:
- data to generate the adherence diversity index (ADI),
- data to generate the organisational diversity index (ODI),
- data to generate the centrality of religiosity scale (CRS).
Considering quantitative and qualitative data
A new religious diversity index may overcome the common underlying assumption that the percentage of a population identifying with a religious group (membership rate) is equal to the percentage of that population who actively participate in that religious group. As known of qualitative research, religions are regularly practiced independently of formal membership, and mempership does not always align with personal religious identity. Drawing a realistic picture of religions in the 21st century must consider this even in indices.
Nevertheless, the new measurement strategies used by CERES for the comparision of three European countries are the first steps for a model of future research. More steps have to follow.