The Future of World Religions (to 2100)
Mike Ervin
The Future of World Religions
Below is a single, coherent narrative summary of The Future of World
Religions (to 2100) that covers demographic projections, growth/decline
patterns, why Africa will shape Christianity and Islam, and likely futures for
Buddhist and Hindu modernities. I drew on the latest UN population work and
major religion-projection research so the load-bearing factual claims
(population shares, regional growth drivers, fertility links) are cited below.
The longue durée: a world reordered
by demography and adaptation
By 2100 the map of global religion will look both familiar and strikingly
different. Global population growth is slowing and expected to peak before the
century’s end; yet where people will live — especially the dramatic expansion
of Africa’s population — will reshape the numerical center and cultural energy
of the world’s faiths. The interplay of fertility, age structure, migration,
conversion/disaffiliation, and differential retention rates will produce
divergent trajectories: Islam and Christianity will remain the largest faiths
but their regional centers will shift; the unaffiliated will continue to shrink
globally though grow in parts of the West; Buddhism is likely to be stable or
fall modestly in share; Hinduism will remain large but concentrated in South
Asia and shaped by modern nationalisms and diasporas.
Big-picture demographic projections
to 2100
United Nations population projections show global population rising more
slowly than earlier forecasts and likely peaking in the later mid-century
before settling around roughly 10–10.3 billion by 2100 under median scenarios.
Most of the additional people this century will be born in sub-Saharan Africa,
which is projected to move from roughly one-sixth of the world’s population
today to a much larger share by 2100 — a shift that concentrates future
fertility, youth cohorts, and thus potential religious growth in African
nations. These broad population shifts are the structural engine behind most
religious projections.
Growth and decline patterns by
religion (the headline moves)
- Islam: Because
Muslim populations today tend to be younger and have higher average
fertility in many countries, Islam is projected to be the fastest-growing
major religion over the 21st century. Extended projection models indicate
Muslims will match and then slightly exceed Christians in global share by
the late 21st century in many modeled scenarios. That growth is
geographically concentrated (large gains in sub-Saharan Africa, continued
growth in parts of Asia, rising Muslim populations in Europe and the Americas
via migration and higher fertility).
- Christianity:
Christianity will likely remain one of the two largest traditions in
absolute numbers, but its center of gravity will continue to move south
and east. Declines in Europe and parts of the Americas due to low
fertility and rising disaffiliation will be offset by strong growth in
sub-Saharan Africa and parts of Asia. In many scenarios Africa becomes the
single most important region for global Christianity’s vitality,
institutions, and theological creativity.
- Unaffiliated /
“nones”: While the unaffiliated share has grown in many high-income
countries, global models suggest the unaffiliated share could plateau or
even decline as most population growth happens in highly religious regions
(especially in Africa and parts of Asia). Locally, however, secularization
and disaffiliation will continue to be major forces in Europe, East Asia,
and increasingly among younger cohorts in parts of the Americas.
- Hinduism and
Buddhism: Hinduism’s absolute numbers are likely to grow with South Asia’s
population but its global share will be shaped by fertility and migration
patterns and by political and social transformations in India and the
diaspora. Buddhism’s global share is projected to be stable or decline
modestly because of low fertility in key East Asian countries (China,
Japan) and pronounced aging. However, Buddhist institutional influence and
new socially engaged forms could still flourish in localized and
transnational ways.
Why Africa will shape Christianity
and Islam
Two structural facts make Africa decisive. First, Africa contains by far
the youngest population today and will supply the largest share of new births
this century; second, religion remains socially central for many African
societies and is closely linked to family structure and fertility behaviors.
Those factors mean that even modest differences in fertility and retention
translate into large numerical gains over time. Practically, this will shift
pastoral leadership, theological production, hymnody, liturgy, and ecclesial
priorities — African churches and Islamic communities will drive much of the
institutional energy, missionary activity, and theological innovation in both
traditions. In short, plurality of Christianity and Islam will be increasingly
African in shape and voice.
The future of Buddhist and Hindu
modernities
- Buddhism: In
conventional demographic terms, Buddhism risks stagnation or a declining
global share because many Buddhist-majority countries have low fertility
and rapidly aging populations. That said, Buddhism’s modern futures are
not reducible to headcounts. Expect continued creative renewal: secular or
“mindfulness” strands will grow in the West and globally; engaged Buddhism
addressing ecology, mental health, and social justice will expand; and
Asian Buddhist institutions may adapt to demographic decline through institutional
consolidation, digital outreach, and diaspora networks. Thus Buddhism’s
cultural influence may remain disproportionate even if its percentage of
global population shrinks.
- Hinduism:
Hinduism will remain numerically large because India and its diaspora
continue to be populous. Political transformations within India
(nationalism, legal and social change), urbanization, and the economic
rise of South Asia will shape how Hindu modernities evolve. We can expect
stronger public expressions of Hindu identity in some settings,
diversified devotional practices in urban middle classes, and robust
diasporic reinvention (temples, festivals, digital communities) that keep
Hindu traditions vital on multiple continents. The intellectual and
institutional face of Hinduism in 2100 will be markedly plural — ranging
from conservative political forms to cosmopolitan, reformist, and
transnational spiritualities.
Institutional, theological, and
geopolitical implications
- Institutionally:
Seminaries, missionary networks, and denominational headquarters will be
pressured to reorient: talent pipelines, funding flows, and theological
education will increasingly cross African and Asian axes rather than
Western ones. New global leadership will arise from countries that are
today seen as mission fields.
- Theologically
and liturgically: Expect richer pluralization of theological emphases —
African and Asian pastoral priorities (communal resilience, poverty,
healing, ritual innovation) will become central themes in global
Christianity and Islam. Inter-religious encounters will intensify in
cities and across diasporas, producing hybrid practices and new social
theologies.
- Geopolitically
and socially: The religious map will interact with migration flows,
climate pressure, and state policies. Countries with youthful, religious
populations may exert outsized cultural influence; conversely, aging and
secularizing populations will shift political debates about welfare,
family policy, and the public role of religion.
Caveats and drivers of uncertainty
Forecasts to 2100 are inherently uncertain. Projections depend on
fertility trends, migration policies, conversion and retention rates, state
repression or protection of religion, pandemics, war, and large social shifts
(education, women’s empowerment, urbanization). Small changes in fertility or
retention in fast-growing regions produce large long-term effects; conversely,
sudden secularizing waves in high-fertility countries would change the
arithmetic rapidly. Use projections as scenarios, not inevitabilities.
Key Takeaways (quick list)
- Global
population likely peaks near mid-century and ends the century around
~10–10.3 billion; Africa supplies most of the century’s population growth.
- Islam is
projected to be the fastest growing major religion and may slightly exceed
Christianity in global share by late century in many modeled scenarios.
- Christianity
will remain large but become increasingly African and Asian in numbers,
leadership, and theological concerns.
- Buddhism’s
global share is likely to be stable or modestly down but its cultural
influence will continue through new social forms and diasporas.
Hinduism
will retain a central role through South Asia and its diaspora, shaped
powerfully by politics, urbanization, and modern institutional forms.
The Future of World Religions (to 2100)
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