The World in Numbers

Pew 2010→2020: +122 million to 2.3B, but share fell 1.8pp (30.6%→28.8%) — growth lags world population, driven down by disaffiliation in Europe/Americas and offset by rapid growth in sub-Saharan Africa (~2.5%/yr per Grokipedia).

Fastest-growing major religion (Pew 2010→2020: +347M, +1.8pp), driven overwhelmingly by the highest fertility rates (TFR ~2.9-3.1) and young median age (23), not conversion.

Pew 2010→2020: +270M to 1.9B (+0.9pp), driven by religious switching away from Christianity in Europe, the Americas and East Asia; unaffiliated majorities in 10 countries by 2020 (up from 7). Long-run Pew projections still show share DECLINING by 2050 (to ~13%) because of low fertility (1.6).

Pew 2010→2020: +126M, growing exactly in step with world population (share flat at 14.9%). Fertility (2.3) near world average; negligible conversion in or out.

Long-run share decline from ~7.3% (1900) to ~5.5% (2025) per Grokipedia; suppressed by state atheism in China and conversion to Christianity/Islam in Africa, though Chinese folk practice has revived since the 1980s.

Pew 2010→2020: -19 million (324M, 4.9%→4.1%) — the only major religion shrinking absolutely, due to very low fertility (1.6) in East Asia and disaffiliation. WRD-style counts are roughly stable around 500-540M.

Up 12% 2010→2020 (Grokipedia); new religious movements grow fastest in urbanizing developing regions.

Tracks Japan's shrinking, secularizing population; most practitioners are syncretic with Buddhism and report no religion in surveys.

Growth via natural increase rather than conversion (Grokipedia); strong diaspora growth in Canada, UK, US, Australia, Italy.

Pew 2010→2020: +6%, share flat at 0.2%. High Israeli fertility offsets assimilation and low fertility in the diaspora.

Formal counts small and steady; broader Taoist-influenced folk practice reviving in China since the 1980s (counted under folk religions).

Formal adherent counts (mainly Korea and Chinese diaspora) are small and stable; Confucian cultural influence spans over a billion East Asians.

Growth via missionary expansion in Africa and the Americas since the mid-20th century (Grokipedia); Grokipedia projects potentially 12M by 2050 if trends persist. Persecuted in Iran, its country of origin.

Grokipedia: 'numbers have remained stable, reflecting low conversion rates and endogamous practices.'

Aging Parsi community with very low fertility and strict non-conversion norms; one of the oldest religions and now among the smallest.