Religious Adherents, 2010 (World Christian Database)1
The country has an area of 364,900 square miles and a population of 40 million, of which 38 million live on the mainland and 2 million on the Zanzibar archipelago, which has a semi autonomous political structure separate from the mainland political system. Current statistics on religious demography are unavailable because religious surveys were eliminated from government census reports after 1967. Religious leaders and sociologists estimate that the Christian and Muslim communities are equal in size, each accounting for 30 to 40 percent of the population, with the remainder consisting of practitioners of other faiths and traditional indigenous religions. However, 99 percent of the population on the Zanzibar archipelago is Muslim.
On the mainland, Muslim communities are concentrated in coastal areas, with some large Muslim minorities also in inland urban areas. Between 80 and 90 percent of the Muslim population is Sunni; the remainder consists of several Shi'a subgroups, mostly of Asian descent. The Christian population is mostly composed of Roman Catholics, Protestants, Pentecostals, Seventh-day Adventists, members of the Church of Jesus Christ of Latter-day Saints (Mormons), and members of Jehovah's Witnesses. There are also active communities of other religious groups, primarily on the mainland, such as Buddhists, Hindus, and Baha'is.
Note: The World Christian Database (WCD) estimates, used in the Religious Adherents section above, count each person as belonging to a maximum of one religious group. For more information, see the WCD methodology document. The U.S. State Department's International Religious Freedom report estimates, used in the Religious Demography section, use less restrictive criteria in which a person who identifies with more than one religion is classified as a follower of each. In certain cases (such as Japan and other nations with strong folk religion traditions), this can cause counts to vary widely between estimates. Users are advised to consult the relevant source documents before determining which counts to cite.
1. The World Christian Database (WCD) is based on the 2600-page award-winning World Christian Encyclopedia and World Christian Trends, first published in 1982 and revised in 2001. This extensive work on World religion is now completely updated and integrated into the WCD online database. Designed for both the casual user and research scholar, information is readily available on religious activities, growth rates, religious literature, worker activity, and demographic statistics. Additional secular data is incorporated on population, health, education, and communications. A dataset with these and the other international measures highlighted on the country pages can be downloaded from this website. Used with permission.
2. The U.S. State Department's International Religious Freedom Report is submitted to Congress annually by the Department of State in compliance with Section 102(b) of the International Religious Freedom Act (IRFA) of 1998. This report supplements the most recent Human Rights Reports by providing additional detailed information with respect to matters involving international religious freedom. It includes individual country chapters on the status of religious freedom worldwide. A dataset with these and the other international measures highlighted on the country pages can be downloaded from this website. These State Department reports are open source.