In less than 20 years the number of Muslim births will exceed Christians births, and could make Islam the world's largest religion by the end of the century, according to a new report.
A just-released Pew Research Center Demographic Study says that Christianity remains the world's largest religion -- there were 2.3 billion Christians in 2015-- but Christianity is growing more slowly due to the shrinking number of believers in Europe.
Meanwhile, the global Muslim population increased by more than 150 million people between 2010 and 2015, to 1.8 billion.
Islam is already the world's fastest-growing religion, because even though Christian births still outpace Muslim births, more Christians are dying in European nations such as England, Germany, Italy and Russia, than are being born.
Conrad Hackett, lead researcher on the Pew study, says "Christianity is literally dying in Europe."
The heart of Christendom is moving from Europe to Africa.
The study also projects that the numbers of Christians and Muslims will be nearly equal by 2060, which is ten years later than a 2015 Pew projection.
It found that for both religions, their growth comes largely from births.
Islam has an advantage in conversions, according to Pew. It says Christianity has lost more members than any other religion in recent years because of people changing their faith.
Immigration is also changing religious demographics.
Demographer David Coleman of Oxford has written that uncontrolled immigration could lead to "finis britanniae," "which simply means the end of Britain," Coleman told CBN News, "and by that, I mean the end of Britain as we know it."
"The point I was making is the change in the number of people and particularly the change in the origins of people, in their religion, in their cultural background, would make Britain unrecognizable compared with the present time."
Pew predicts that except for Islam and Christianity, all major world religions are projected to make up a smaller percentage of the global population in 2060 than they did in 2015.