Between 2010 and 2020, the global population grew significantly, and most major religious groups expanded alongside it. Yet amid these shifts, Hinduism remained remarkably stable - both in absolute numbers and as a share of the global population - even as other religions surged or declined.
Based on over 2,700 censuses and surveys, a report by Pew Research Center highlights how Hinduism maintained its position through a combination of demographic steadiness and minimal religious switching.
Hinduism: Stable growth in a changing world
Hinduism grew by around 126 million adherents over the decade, reaching about 1.2 billion followers by 2020. Its global share remained constant at 14.9%, showing that the Hindu population growth closely matched the world’s population growth.
Unlike several other faiths, Hinduism experienced minimal religious switching — few people converted into or out of the religion. Fertility rates among Hindus were near the global average, contributing to steady growth without sharp fluctuations. This demographic and cultural stability helped Hinduism maintain its status as the world’s third-largest religion after Christianity and Islam.
Key findings about other religions
Christianity: Still dominant but losing share
Christianity remained the world’s largest religion, growing from 2.18 billion to 2.30 billion adherents. However, its global share declined from 30.6% to 28.8%. This reduction was not due to fertility or mortality patterns, but due to widespread religious switching, especially in the West. According to the report, for every person who becomes Christian, three leave the faith, mostly becoming unaffiliated.
By 2020, Christians were the majority in 120 countries and territories, down from 124 a decade earlier. Countries such as the United Kingdom, Australia, France and Uruguay all saw their Christian populations dip below the 50% mark.
Islam: Fastest-growing major religion
Islam experienced the most rapid growth, adding 347 million adherents and reaching approximately 2 billion followers by 2020. Its share of the global population rose from 23.8% to 25.6%. This expansion was driven almost entirely by demographic factors — Muslims had a younger median age (24 vs 33 for non-Muslims) and higher fertility rates. Religious switching played little to no role.
Religiously unaffiliated: Gaining through atheism
The religiously unaffiliated - often referred to as "nones" - grew from 23.3% to 24.2% of the world’s population. This growth occurred despite the group’s demographic disadvantages: older age structure and lower fertility. The rise of the unaffiliated was largely fuelled by disaffiliation from Christianity, especially in developed countries where secularisation is on the rise.
Buddhism: The only major decline
Buddhists were the only major religious group to decline in absolute numbers, dropping from 343 million to 324 million adherents. This contraction was due to low fertility and some degree of religious switching. With an older demographic profile and no significant conversion gains, Buddhism lost ground while other faiths grew or held steady.
Judaism
The Jewish population grew slightly from 13.8 million to 14.8 million between 2010 and 2020, holding a constant global share of 0.2%. Judaism’s demographic profile is relatively old, and conversion activity is limited, so growth remains modest and steady.
A combined category of smaller religions — including Jains, Baha'is, folk religions and others — maintained a consistent global share of 2.2%. Their growth was roughly in line with overall population expansion, with little influence from switching or unique demographic trends.
Why these changes occurred
Two main forces shaped global religious change during the decade: Demographics - younger populations and higher fertility rates contributed to faster growth, with Islam and Hinduism benefiting most from this trend, and religious switching - Christianity experienced major losses due to disaffiliation, while the unaffiliated gained primarily through former Christians; Hinduism, Islam, and Judaism were largely unaffected by switching patterns.
What the survey means
While Christianity continues to lead in absolute numbers, its share of the world’s population is shrinking. Islam is expected to grow steadily and may approach parity with Christianity by the mid-21st century. The unaffiliated group is gaining ground in culturally secular societies, despite demographic disadvantages.
In contrast, Hinduism's consistency, driven by moderate fertility, stable demographics and minimal switching, reflects its enduring position in the global religious landscape. It may not be the fastest growing or most discussed, but it remains a demographic and cultural constant in a world of shifting religious identities.