NEW YORK — Christianity may have been founded in the Middle East but few Christians remain in the region, a study by the Pew Forum on Religion and Public Life revealed.

According to Pew’s newly released December 2012 “Global Religious Landscape Study,” just 0.6 percent of the world’s 2.2 billion Christians now live in the Middle East and North Africa. Christians make up only 4% of the region’s inhabitants, drastically down from 20% a century ago and marking the smallest regional Christian minority in the world.

Fully 93% of the region is Muslim, and 1.6% is Jewish.

The study is based on an analysis of country-specific data from more than 2,500 national censuses, large-scale surveys and official population registers. It measures self-identification.

The world’s largest single Christian country by share of the global Christian population is the United States, with 11% of the world’s Christians, followed by a list that reflects the religion’s global reach: Brazil (8%), Mexico (5%), Russia (5%), the Philippines (4%), Nigeria (4%), China (3%), the Democratic Republic of the Congo (3%), Germany (3%) and Ethiopia (2%). These 10 countries account for roughly half of all Christians, though 157 of the 232 countries surveyed have Christian majorities.

Islam, which has some 1.6 billion adherents worldwide, is more concentrated in Asia and the Middle East, the report found. Some 62% of Muslims live in Asia and the Pacific region, while 20% live in the Middle East and North Africa.

The four largest national Muslim populations are all in Asia: Indonesia, India, Pakistan and Bangladesh. The fifth is Nigeria, in West Africa. Muslims are the youngest religious affiliation worldwide, with a median age of 23, followed by Hindus (26), Christians (30) and Buddhists (34). Jews are the oldest at median age of 36.

Among the study’s other findings, fully 1.1 billion people, or 16% of humanity, are religiously unaffiliated, including atheists, agnostics and those who decline to identify with a religion.

The figure does not necessarily indicate a lack of religious feeling, only a refusal to formally identify with a particular religion. As the Pew report notes, “many of the religiously unaffiliated have some religious beliefs.” As many as 68% of unaffiliated American adults, 30% of unaffiliated French adults and 7% of unaffiliated Chinese adults said they believed “in God or a higher power.”