Personal religious affiliation:
Comparing the U.S. with the rest of the world

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Definition of religion:

We define religion very broadly: "Religion is any specific system of belief about deity, often involving rituals, a code of ethics, a philosophy of life, and a worldview." Thus we consider Christianity, Islam, Judaism, Native American Spirituality, and Neopaganism to be religions. We also include Agnosticism, Atheism, Humanism, Ethical Culture etc. as religions, because they also contain a "belief about deity" -- their belief is that they do not know whether a deity exists, or they have no knowledge of God, or they sincerely believe that God does not exist.

Religious diversity:

The United States has been described as the most religiously diverse country in the world. In spite of this, it is relatively free of religiously motivated violence. Some observers attribute this to the First Amendment of the U.S. Constitution which guarantees:

• A wall of separation between church and state.
• Freedom of adults to follow their own religious and spiritual path without oppression or discrimination.

All of the world's major religions, from Asatru to Zoroastrianism are practiced throughout the U.S. However, the percentage of adherents of a given religion in the U.S. is often quite different from the corresponding value elsewhere in the world. For example:

• About 75% of American adults identify themselves with Christianity; only 33% of the world's population is Christian.
• About 2% of Americans regard themselves as Muslim; the corresponding world-wide figure is 20%.

It may make sense for some meditation rooms, or school libraries or other religious locations visited by the public, to provide sacred texts on the basis of the popularity of religions within the U.S. However, meditation rooms located in international airports on the East and West coast might consider the religious makeup of their international visitors as well.

Estimating the size of each religious group:

Listed in the table below are the major religions, in order of decreasing numbers of adherents in the U.S. These numbers are based on the American Religious Identification Survey (ARIS). ₁ This was a telephone survey of 50,281 American households conducted in 2001 between February and June. Often, the religions of both partners or spouses were recorded, so the sample size is probably on the order of 75,000. This is unusually massive, compared to most public opinion surveys which only sample about 1,000 people. They were asked the simple question: "What is your religion, if any?"

Various almanacs and religious encyclopedias list some data that are very  different from the ARIS survey data. The former are generally based on information provided by individual denominations -- data that is often not particularly reliable.

• Some faith groups count as a member anyone who has been baptized;
• Others count only active members;
• Some include only adult members;
• Others count children as well;
• Some pad their numbers;
• Others refuse to release membership data.

Comparison of religions in the U.S. and the world:

The numbers of U.S. adherents which are shown (in brackets) were taken from the World Almanac and Book of Facts 2005. The lack of agreement between the ARIS and Almanac are quite remarkable for some faiths. Another estimate of worldwide adherents is provided by Adherents.com. ₁₁

Notes and references used:

The following information sources were used to prepare and update the above essay. The hyperlinks are not necessarily still active today.

1. American Religious Identification Survey (ARIS) data for 2001 is at: http://www.gc.cuny.edu/ This is a PDF file. You may require software to read it. Software can be obtained free from: 

2. Based on a total U.S. adult population of 207,980,000 -- persons who have reached their 18th birthday at the time of the survey.

3. Based on The World Almanac and book of facts, 2005," Page 734. These data were based on the 2004 Encyclopedia Britannica Book of the Year.

4. Based on a world population of 6,288 million.

5. Estimates by some American Muslim groups are as high as seven million.

6. Agnostics are lumped together with the "Nonreligious" in the Encyclopedia Britannica data.

7. Atheists, Humanists and Secularists are lumped together as "Atheists" in the 2004 Encyclopedia Britannica Book of the Year data and total 148.7 million (2.4% of the world's population)

8. Unitarian Universalists follow a variety of belief systems: Agnosticism, Atheism, Buddhism, Christianity, Humanism, Judaism, Wicca and other Neopagan religions, etc. No specific theological beliefs are imposed by the denomination.

9. This number may be grossly underestimated. Because of considerations of personal safety, many Wiccans and other Neopagans would be unwilling to reveal their faith to a stranger on the phone. Also, the group has been doubling in size every 30 months or so. By now, this religion may be the fourth or fifth most popular faith in the U.S.

10. Many Aboriginal religions are taught by an oral tradition without having been set down in book form.

11. "Major Religions of the World, Ranked by Number of Adherents," Adherents.com, at: http://www.adherents.com/

12. An estimate by an authority in the Church of Scientology® based on the number of people who have participated in a basic or major service of the Church.

Copyright © 2005 to 2008 by Ontario Consultants on Religious Tolerance
Originally posted: 2005-DEC-11
Latest update: 2008-AUG-10
Author: B.A. Robinson

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