New stats from the Pew Forum on Religion & Public Life study on The Global Religious Landscape.
84% of the world's 7 billion people adhere to some form of religion.
Christians are the largest group, 2.2 billion (32%).
Muslims are the second largest, 1.6 billion (23%).
"Nones" (no religious affiliation or don't believe in God) are 1.1 billion (16%).
This makes "nones" about the same size as the Catholic church worldwide.
One out of six people worldwide does not have a religious identity.
Next largest group is Hindus, 1 billion (15%).
Then Buddhists, 500 million (7%).
Then Jews, 14 million (.2 percent).
Note that after Buddhists, all other religious traditions are miniscule as a percentage of the global population.
400 million people (6%) practice folk traditions.
An additional 58 million people (~1%) belong to other religions, such as Baha'i, Jainism, Sikhism, Shintoism, Taoism, Tenrikyo, Wicca and Zoroastrianism.
The nation with the most Christians is the United States (243 million), although Christians are widely distributed around the globe.
The majority of the world's religiously unnafiliated live in the Asia-Pacific region, especially China (700 million).
There are 51 million religiously unaffiliated Americans.
The religiously unafiliated 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, while Muslims, Hindus and Christians have the lowest. Median age is a predictor of how religious groups will grow.
One warning from the researchers is that such surveys sometimes over-estimate certain population groups, especially Christians.