* Many have no link to a religion, but may also be spiritual
* Christianity is largest and most widely spread faith
* Islam is second religion, set to grow in future
Dec 18 (Reuters) - People with no religious affiliation make
up the third-largest global group in a new study of the size of
the world's faiths, placing after Christians and Muslims and
just before Hindus.
The study, based on extensive data for the year 2010, also
showed Islam and Hinduism are the faiths mostly likely to expand
in the future while Jews have the weakest growth prospects.
It showed Christianity is the most evenly spread religion,
present in all regions of the world, while Hinduism is the least
global with 94 percent of its population in one country, India.
Overall, 84 percent of the world's inhabitants, which it
estimated at 6.9 billion, identify with a religion, according to
the study entitled "The Global Religious Landscape" issued by
the Pew Forum on Religion and Public Life on Tuesday.
The "unaffiliated" category covers all those who profess no
religion, from atheists and agnostics to people with spiritual
beliefs but no link to any established faith.
"Many of the religiously unaffiliated do hold religious or
spiritual beliefs," the study stressed.
"Belief in God or a higher power is shared by 7 percent of
unaffiliated Chinese adults, 30 percent of unaffiliated French
adults and 68 percent of unaffiliated U.S. adults," it said.
Exact numbers for religious populations are impossible to
obtain and estimates for the size of the larger faiths can vary
by hundreds of millions. This study by the Washington-based Pew
Forum appears to be one of the most extensive to date.
Pew Forum demographer Conrad Hackett said the 2,500
censuses, surveys and population registers used to compile the
report did not allow a further breakdown to estimate the world
population of atheists and agnostics.
"It's not the kind of data that's available for every
country," he said. "A census will typically ask what your
religion is and you can identify a number of particular
affiliations or no religion.
An age breakdown showed Muslims had the lowest median age at
23 years, compared to 28 for the whole world population. The
median age highlights the population bulge at the point where
half the population is above and half below that number.
"Muslims are going to grow as a share of the world's
population and an important part of that is this young age
structure," Hackett said.
By contrast, Judaism, which has 14 million adherents or 0.2
percent of the world population, has the highest median age at
36, meaning its growth prospects are weakest.
Hackett noted that Israel, which has 40.5 percent of the
world Jewish population, had a younger age structure than the
United States, where 41.1 percent of the world's Jews live.
Global Christianity's median age is 30 and Hinduism's 26.
With a median age of 34, the growth prospects for religiously
unaffiliated people are weak, the study showed.
The study estimated Christianity was the largest faith at
2.2 billion adherents or 31.5 percent of the world's population.
The Roman Catholic Church makes up 50 percent of that total,
with Protestants -- including Anglicans and non-denominational
churches -- at 37 percent and Orthodox at 12 percent.
There are about 1.6 billion Muslims around the world, or 23
percent of the global population. "The overwhelming majority
(87-90 percent) are Sunnis, about 10-13 percent are Shia
Muslims," the study said.
Among the 1.1 billion unaffiliated people around the world,
over 700 million, or 62 percent of them, live in China alone,
where they make up 52.2 percent of the Chinese population.
Japan comes next with the second largest unaffiliated
population in the world with 72 million, or 57 percent of the
national population. After that comes the United States, 51
million people -- 16.4 percent of all Americans -- said they
have no link to an established faith.
The world's Hindu population is concentrated mostly in
India, Nepal and Bangladesh. Half of the world's Buddhists live
in China, followed far behind by Thailand at 13.2 percent of the
world Buddhist population and Japan with 9.4 percent.
The study found that about 405 million people, or about 6
percent of the world population, followed folk religions such as
those found in Africa and China or among Native American and
Australian aboriginal peoples.
Another 58 million, or nearly 1 percent of the world
population, belonged to "other religions" including Baha'i,
Taoism, Jainism, Shintoism, Sikhism, Tenrikyo, Wicca and
Zoroastrianism. Most were in the Asia-Pacific region.
The study said that 97 percent of the world's Hindus, 87
percent of its Christians and 73 percent of its Muslims lived in
countries where they were a large to overwhelming majority.
Christians make up the majority in 157 countries and Muslims
in 49, including 19 of the 20 states in the Middle East and
North Africa, with the exception of Israel.
By contrast, Hindus are in the majority only in India, Nepal