Adherents.com is a growing collection of over 43,870 adherent statistics and religious geography citations: references to published membership/adherent statistics and congregation statistics for over 4,200 religions, churches, denominations, religious bodies, faith groups, tribes, cultures, movements, ultimate concerns, etc. The religions of the world are enumerated here.
Basically, researchers can use this site to answer such questions as "How many Lutherans live in Wisconsin?", "What are the major religions of India?", or "What percentage of the world is Muslim?" We present data from both primary research sources such as government census reports, statistical sampling surveys and organizational reporting, as well as citations from secondary literature which mention adherent statistics.
Famous and influential: Adherents.com also has detailed lists of influential and famous adherents of over 100 different religious groups (famous Methodists, famous Jews, famous Catholics, famous Zoroastrians, famous Jehovah's Witnesses, famous Theosophists, etc.), and lists of prominent people (actors, politicians, authors, U.S. presidents, artists, musicians, Supreme Court justices, film directors, etc.) classified by religious affiliation. These lists are linked to thousands of detailed religious/spiritual biographies.
Note: be aware that many of the resources have not be updated recently.