This site, which is not affiliated with any religious organization, summarizes religious statistics found in books, journals, or Web sites. It provides a list of the world's major religions with the number of adherents. It also provides statistics by location (within the U.S., by state) or religious affiliation. The source for the statistics is also given with the date of publications, so information can be verified.
This is a reference resource produced by the CIA with almanac-style information about the countries of the world. The Factbook is available online and is partially updated every week. It provides a two- to three-page summary of the demographics, geography, communications, government, economy, and military of 266 entities including U.S.-recognized countries, dependencies, and other areas in the world.