Islam World's Fastest Growing Faith by Birth

Islam is the world's fastest growing religion, according to a new study from the Pew Research Center.

The study says that by 2050, Christianity will still be the world's largest religious group, coming in at 2.92 billion followers.

But Islam will grow rapidly to come in a close second at 2.76 billion. That's more than a billion members higher than right now.

That growth will come mostly because Muslims have more children, and the world's current Muslim population is much younger than the Christian population.

By 2050, the study shows Muslims will make up 10 percent of the overall population of Europe. And while India will retain a Hindu majority, it will also have the largest Muslim population of any country in the world, surpassing Indonesia.

In the United States, Christians are expected to decline from more than three-quarters of the population in 2010 to two-thirds in 2050. And Islam is on track to become the largest non-Christian religion in the U.S, surpassing Judaism.

The largest Christian growth in the world will likely come in sub-Saharan Africa, which will become home to four out of every 10 Christians.