The number of babies born to Muslims is expected to overtake those born to Christians within two decades, making Islam the world’s largest religion by 2075, according to new analysis of data by the Pew Research Center.

People with no religious affiliation are set to shrink as a proportion of the world’s population as a result of their declining birthrate and growing numbers of Muslims and Christians.



The analysis points to modest but significant demographic shifts in religious affiliation over the coming decades, as populations in the global south continue to grow rapidly and Christian populations in Europe age and die.



Between 2010 and 2015, an estimated 31% of babies born in the world were to Muslim parents, far exceeding the 24% share of the world’s population held by Muslims. 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.



That is set to change, owing to the relatively young age profile of Muslims and their higher fertility rates. Between 2030 and 2035, slightly more babies (225 million) will be born to Muslims than to Christians (224 million). Between 2055 and 2060, the gap is expected to widen to 6 million – 232m births to Muslims, and 226m to Christians.



Meanwhile, deaths among Christians in Europe are far outstripping births. In Germany, between 2010 and 2015, there were an estimated 1.4m more deaths than births among Christians. Pew said the pattern was expected to continue across much of Europe in the decades ahead.



Despite a relatively young and fertile Christian population in sub-Saharan Africa, Christians have accounted for a disproportionate 37% of the world’s deaths in recent years.



“In contrast with [the] baby boom among Muslims, people who do not identify with any religion are experiencing a much different trend,” said Pew. Religiously unaffiliated people make up 16% of the global population, but only produce 10% of the world’s babies.



“This dearth of newborns among the unaffiliated helps explain why religious ‘nones’ (including people who identify as atheist or agnostic, as well as those who have no particular religion) are projected to decline as a share of the world’s population in the coming decades.”



By 2055-2060, 9% of all babies will be born to religiously unaffiliated women, while more than 70% will be born to either Muslims (36%) or Christians (35%), said Pew.



Religiously unaffiliated people are “heavily concentrated in places with ageing populations and low fertility, such as China, Japan, Europe and North America. By contrast, religions with many adherents in developing countries – where birthrates are high and infant mortality rates have been falling – are likely to grow quickly. Much of the worldwide growth of Islam and Christianity, for example, is expected to take place in sub-Saharan Africa,” said Pew.

In 2015, of the world’s 7.3bn people, Christians were the largest religious group, at 31%. Muslims were second at 24%, followed by religious “nones” (16%), Hindus (15%) and Buddhists (7%). Jews, adherents of folk religions (faiths associated with a particular group of people, ethnicity or tribe), and followers of other religions made up smaller shares of the global population.

The projections did not assume that all babies would retain the religion of their parents, but attempted to take religious switching into account, although “conversion patterns are complex and varied”, said Pew.

