'No religion' third world group after Christians, Muslims
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.