Adherent statistics are usually not precisely comparable . Wherever possible the supporting material makes it clear whether statistics are from surveys, census data, organizational reporting, or other sources. Knowledge of the source of the statistics, as well as further knowledge of the particulars of a cultural, religious or regional group are necessary for an adequate understanding of the sociological implication of this type of data. Furthermore, although this listing is the largest of its kind, it is not exhaustive . There are faith groups, churches and philosophies which are NOT listed here, especially smaller groups outside the U.S. Broad philosophies and movements not defined by organized religious bodies are, of course, more difficult to obtain statistics for.
Some sociologists define religion as a belief system shared by a group of individuals.
The database has thousands of broad classifications, religions, branches, individual churches, etc., and most people fit under multiple labels, but no individual can be completely categorized by any of these labels. 40,190 adherent records.