Of the world's 6.9 billion people, 2.2 billion or 32 percent are Christians, Pew reported Dec. 18. While only 12 percent of Christians live in North America, the vast majority of Christians, 99 percent, live outside the Middle East-North Africa region where Christianity began.
Researchers did not study the degree to which people actively practice their faiths, but relied on the subjects' self-identification of their religious affiliation.
The majority of the world's other religions lives in the Asia-Pacific region, including nearly all Buddhists and Hindus, and most Muslims and the religiously unaffiliated, researchers found. While 58.8 percent of the world's population lives in the Asia-Pacific region, it is home to 99 percent of Hindus and Buddhists, 62 percent of Muslims and 76 percent of the religiously unaffiliated.
Pew reported that the world's population includes 1.6 billion Muslims, 1 billion Hindus, nearly 500 million Buddhists, 400 million adherents of various folk and traditional religions, 58 million adherents the study confined to the category of "other," comprised of many religions including Baha'i faith, Jainism, Sikhism, Shintoism, Taoism and Wicca.
A plurality of the world's 14 million Jewish people, 44 percent, live in North America, while 41 percent live in the Middle East and North Africa, nearly all of them in Israel, the study found.
In the U.S., 78 percent, or 243,060,000 of the country's 310,390,000 people are Christian, the study found. The U.S. also has 50,980,000 religiously unaffiliated, 5,690,000 Jewish people, 3,570,000 Buddhists, 2,770,000 Muslims, 1,790,000 Hindus, 630,000 adherents to folk religions and 1,900,000 affiliated with other religions.
The Global Religious Landscape: A Report on the Size and Distribution of the World's Major Religious Groups as of 2010 encompasses more than 230 countries and territories. Based on more than 2,500 censuses, surveys and population registers, the research is part of the Pew-Templeton Global Religious Futures Project, analyzing religious change and its impact on societies around the world.
Globally, about half of all Christians are Catholic. An estimated 37 percent of Christians are Protestant, including Anglican, independent and nondenominational churches. The Orthodox Communion, including the Greek and Russian Orthodox, make up 12 percent of Christians.
Researchers categorized Christian Scientists, Mormons and Jehovah's Witnesses as "viewing themselves as Christian," and computed them as comprising about 1 percent of the global Christian population.
Most of the world's population, 5.8 billion or 84 percent, affiliates with a particular religion, leaving 1.6 billion, or 16 percent, with no religious affiliation, the study found. But many with no religious affiliation hold religious or spiritual beliefs, such as a belief in God or a universal spirit, while not identifying with a particular religion.
The study found that some religions have much younger populations, determined in part by the growth rate of countries where the religions are largely found. For example, religions concentrated in China tend to be older, because the population growth is slower.
The median age of the world's overall population is 28, while the median age of Christians is 30, the study found.
The full report is available here.