A new report on global religious identity shows that while Christians and Muslims make up the two largest groups, those with no religious affiliation -- including atheists and agnostics -- are now the third-largest "religious" group in the world.
The study, released Tuesday by the Pew Forum on Religion & Public Life, found that more than eight in 10 (84 percent) of the world's 7 billion people adheres to some form of religion. Christians make up the largest group, with 2.2 billion adherents, or 32 percent worldwide, followed by Muslims, with 1.6 billion adherents, or 23 percent worldwide.
Close behind are the "nones" -- those who say they have no religious affiliation or say they do not believe in God -- at 1. 1 billion, or 16 percent. That means that about the same number of people who identify as Catholics worldwide say they have no religion.
"One out of six people does not have a religious identity," said Conrad Hackett, a primary researcher and demographer on the study. "But it is also striking that that overwhelming majority of the world does have some type of religious identity. So I think people will be surprised by either way of looking at it."
The next largest groups, the report finds, are Hindus (1 billion people, or 15 percent), Buddhists (500 million people, or 7 percent) and Jews (14 million people, or 0.2 percent). More than 400 million people -- 6 percent -- practice folk traditions from African, Chinese, Native American or Australian aboriginal cultures.
An additional 58 million people -- slightly less than 1 percent of the global population -- belong to "other" religions, such as the Baha'i faith, Jainism, Sikhism, Shintoism, Taoism, Tenrikyo, Wicca and Zoroastrianism.
In addition to the numbers of adherents, the study also looks at where they live. Christians are the most evenly distributed, while Jews are fairly evenly divided between North America and the Middle East. The United States has the highest number of Christians of any nation, at more than 243 million, or 78 percent of the total U.S. population.
Meanwhile, the majority of the world's religiously unaffiliated -- 76 percent -- live in the Asia-Pacific region, with 700 million in China alone, where religion was stifled during the Cultural Revolution.
The report found nearly 51 million religiously unaffiliated Americans, or about 16.4 percent of the U.S. population. That number is smaller than the 19 percent of Americans Pew reported earlier this year. Researchers attribute this discrepancy to the fact that their 2012 report was based on information from adults only, and the newest report includes the religious adherence of children, which tends to be higher than that of adults.
And while the number of the religiously unaffiliated is high, researchers are careful to point out that they are by no means homogeneous.
Surveys considered in this report show that 7 percent of unaffiliated Chinese report a belief in God or some other high power, while that number among the unaffiliated French is 30 percent, and among Americans it climbs to 68 percent. In China, 44 percent of unaffiliated adults say they have worshiped at a graveside or tomb in the past year.
The report covers 230 countries and is drawn from more than 2,500 censuses, surveys and population records accrued through 2010. It marks the first attempt to pin down a global religious landscape using such records, Hackett said.
Other findings include:
- About three-quarters (73 percent) of the world's people live in countries where their religion is in the majority, mostly Christians and Hindus.
- The religiously unaffiliated are in the majority in six nations: China, the Czech Republic, Estonia, Hong Kong, Japan and North Korea.
- The unaffiliated, Buddhists and Jews have the highest median age (34, 34 and 36 respectively) while Muslims, Hindus and Christians have the lowest (23, 26 and 30 respectively). Median age is a predictor of how religious groups will grow, as those with a younger age have more women of child-bearing age.
Ryan Cragun, a religion sociologist at the University of Tampa who studies the nonreligious, said the numbers on the unaffiliated are not surprising. But he cautions that surveys that rely on secondary data, such as censuses, and self-reporting often over calculates some groups, such as Christians.
"The real question is whether or not the nonreligious are outpacing the religious when it comes to growth," he said.
That and other issues, such as migration, age range and mortality will be covered in future reports, Pew researchers said. A more in-depth report on the religiously unaffiliated is planned for 2013.