The Pew Research Center released their Future of World Religions report earlier this month. The report looks specifically at growth projections for religions between 2010 and 2050, as well as the driving forces behind the changes.

The Study’s Highlights

According to Pew’s projections, in 2050…

• The world population will be 9.3 billion, up from 6.9 billion in 2010.

• Christians will make up 31.4% of the population in 2050, the same percentage they made up in 2010.

• Muslims will make up 29.7% of the population, up from 23.2% in 2010. (Muslims will outnumber Christians by 2070, by the way.)

• Hindus will go from 15.0% in 2010 to 14.9% in 2050. Buddhists will drop from 7.1% to 5.2% during that time. Folk religions? They’ll drop from 5.9% to 4.8%. Jews will stay at 0.2%.

• The religiously ‘Unaffiliated’ will drop from 16.4% in 2010 to 13.2% in 2050.

The Driving Forces

One factor driving changes in religious adherence is what Pew calls “religious switching,” which is simply conversion into, or out of, a given religion. Most religions will see no substantial cumulative effect, with the exception of Christianity, which will lose an estimated 66,000,000 adherents, mostly to the unaffiliated category.

Religious switching figures to be only a regional drop in the bucket compared to the primary global growth engine for organized religion: Sexual reproduction.

The statistics show adherents to the two largest Abrahamic religions will breed more frequently than the rest of the globe over the next three and a half decades. The average global fertility rate is 2.5 children per woman, while Christians have 2.7 children per woman, and Muslims have 3.1. Christians and Muslims are the only religious groups that reproduce above the global average.

Meanwhile, the religiously unaffiliated produce just 1.7 children per woman, well below the 2.5 global average, and even below the 2.1 replacement level necessary to maintain a stable population.

Since children tend to inherit their parents’ religion, Pew cites fertility rates as the largest driver of religious growth of the next few decades.

Additionally, the data show a relatively large percentage of the Christian and Muslim population are at an age where they are still young enough to have children in the future — 27% of Christians and 31% of Muslims are under the age of 15. Only 19% of the religiously unaffiliated are under 15.

The United States

According to Pew, the U.S. will largely defy global religious trends over the next few decades. Muslims will more than double, but will do so given a relatively small base of adherents, going from 0.9% in 2010 to 2.1% in 2050. Christians, meanwhile, will drop from 78.3% to 66.4%, while the religiously unaffiliated will climb to 25.6% in 2050, up from 16.4% in 2010.

Europe is projected to mirror the trends in the U.S. The Muslim population will nearly double, rising from 5.9% in 2010 to 10.2% in 2050. Christians will drop from 74.5% down to 65.2%, while the religiously unaffiliated will climb from 18.8% to 23.3% in the same time period.

Pew projects the majority of the religious switching away from Christianity (~75%) will take place in North America and Europe, with over 50,000,000 people “de-converting” from their Christian faith to become “Nones.”

Images courtesy of: NASA — Pew Research Center