Ever wonder how many Christians there are in the world? What about Muslims? Hindus? Jews? Or how many people belong to religious groups?
Answers to those questions are now available, thanks to The Global Religious Landscape, a new survey by the Pew Forum on Religion and Public Life.
Using data available from more than 2,500 national censuses and large-scale surveys to arrive at its estimates, the survey--considered the most comprehensive to date--found that 5.8 billion of the world's 6.9 billion people identified with some form of religion.
Of that number, 2.2 billion said they are Christians, making Christianity the world's largest religion. Next is Islam, with 1.6 billion followers, Hinduism with one billion and Buddhism with nearly 500 million.
Another 400 million people say they practise folk or traditional religions, including North American and Australian Aborigine religions.
The remainder belong to other religions, such as the Baha'i faith, Judaism, Jainism, Sikhism, Shintoism, Taoism, Tenrikyo and Zoroastrianism, to name a few.
But not everyone is part of a religious group--1.1 billion people don't identify with any religion, making the unaffiliated the third-largest group worldwide behind Chrisians and Muslims and about equal with the size of the world's Catholic population.
Most of the world's unaffiliated are found in countries like China, with 700 million, followed by Japan with 72 million and the U.S. with 51 million. In Canada, over eight million people say they have no religious affiliation.
But not being part of a religious group doesn't mean people don't have a belief of some sort; the survey found that many who don't belong to a religious group say they believe in God or a universal spirit or pursue individual spiritual paths.
When it comes to geographic dispersion, Christianity is the most evenly widespread group, with 26 per cent of Christians living in Europe, 24 per cent in Latin America and the Caribbean, 24 per cent in sub-Saharan Africa, 12 per cent in North America and 13 per cent in Asia-Pacific.
Significantly, barely more than one per cent of Christians today are found in the Middle East, where the faith originated.
Most of the world's Muslims (62 per cent) live in the Asia-Pacific region, with 20 per cent in the Middle East and North Africa, 16 per cent in sub-Saharan Africa, three per cent in Europe and less than one per cent in North America.
The Asia-Pacific region is also home to most of the world's Buddhists and Hindus; 99 per cent of followers of both religions live in that region.
Jews are concentrated primarily in North America (44 per cent) and the Middle East/North Africa region (41 per cent). More than four-fifths of all Jews live in the U.S. and Israel; about three per cent are found in Canada.
When it comes to age of adherents, the survey found the median age of Muslims, at 23 years, and Hindus, 26, is younger than the median age of the world's overall population at 28. The median age for Christianity is 30; for Judaism, it is 36.
What to take from a survey like this? One thing to note is that, despite all the recent media coverage of atheism in the media, it's safe to say that religion has not gone away--people still seem to have a need to believe or belong to a religious group.
Another is the effect of median age, which Pew demographer Conrad Hackett notes is crucial to understanding which religions will grow in the future and which will decline. According to Hackett, the young median age for Muslims and Hindus "indicates that they have a significant growth potential."
A third is the continued dominance of Christianity -- one in three people in the world identify with that faith. Although many Christians today seem to think there is a war on Christianity, the size and reach of that religion suggests, as Max Fisher put it in the Washington Post, that if there is such a war "in global terms, it doesn't seem to be doing very well."
But an important takeaway for me is this question: If the majority of the world's population is religious, and if almost all the world's religions have some version of what is called the Golden Rule, why are there so many wars and conflicts, and why do so many people suffer from hunger, poverty and injustice?
That's a question no survey, no matter how comprehensive, can answer.