While Christianity remained the largest religious group globally in 2015 - comprising nearly a third (31 per cent) of the world's 7.3 billion people - its number is in decline in Europe.
The Washington-based nonpartisan think tank said in an analysis report published on Wednesday that Muslims are projected to be the world's fastest-growing major religious group over the coming decades and in less than 20 years from now. In the same period, 33% of the world's babies were born to Christians, only slightly higher than their 31% share of the global population.
The Pew projections indicate that, between 2030 and 2035, as many as 225 million babies will be born to Muslims, while 224 million will be born to Christians.
But among Christians in Europe the reverse is true: Deaths outnumbered births by almost 6 million during this brief period.
Still, the baby boom among Muslims and Christians is projected to help both religions capture a larger share of the global population by 2060, even as all other religions - and the unaffiliated population - lose ground.
Among the religiously unaffiliated, births outpaced deaths by around one million.Outside of Europe Christianity continues to grow. In recent years, Christians have had more babies than any other religious group worldwide. But it gained more than 100 million devotees due to the difference in births and deaths.
According to several recent studies, Orthodox Jews are the only fast-growing part of U.S. Jewry's religiously identified Jewish community, which increases their political and economic strength, Cohen said.
People with no religion, meanwhile, face a "birth dearth", the research found, likely leading to a significant fall in numbers.
The report clarifies that just because it tallies babies born to mothers of certain religions, that doesn't mean that those babies will remain in the religion their mother is affiliated with. It also said that the country will continue to have largest Hindu population in the world, which may rise to to 1.3 billion aprroxiametely.
In total, Christians were the largest religious group on Earth in 2015, while Muslims were the second largest group.
However, these figures are set to change because of the relatively young age profile of Muslims and their higher fertility rates. By 2060, 9% of the global unaffiliated population will live in the United States alone, according to the projections.
"Babies born to Muslims will begin to outnumber Chistian births by 2035". By contrast, the relatively young population of Muslims has meant higher fertility rates as a whole across Muslim populations. However, they only produce 10 percent of the world's babies.