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Research Process: World Religions by Population

A public record of the questions, source selection, rejected evidence, decision criteria, and update conditions behind this article.

Research Process: World Religions by Population

Environment

Research Instruction

The research input requested an overview of world religions and religious population distribution. Follow-ups requested major-religion headings, numbers, country shares, denominations or branches, enough detail to understand smaller religions by count and country, and a chapter on how far Judaism and evangelicals should be connected when reading Palestine and Israel. Repository policy treats this as a durable public research report, so the work is saved as synchronized Japanese and English article content, source notes, and research logs.

Process

  1. Checked Pew Research Center’s 2025 global religious composition estimates and used the seven-category world totals and shares as baseline data.
  2. Extracted top-country tables for Christians, Muslims, unaffiliated people, Hindus, Buddhists, other religions, and Jews from the Pew 2025 report PDF appendix.
  3. Checked Pew 2011 Global Christianity, Pew 2009 Global Muslim Population, Pew 2012 Buddhists, Pew 2021 India survey material, and Pew 2020 Jewish Americans for denomination and branch context.
  4. Checked Government of India PIB material linked to the 2011 census for named smaller-religion counts that Pew’s combined “other religions” category cannot separate.
  5. Checked World in Data and Pew methodology material for limits around self-reporting, census categories, unaffiliated identity, and East Asian ritual practice.
  6. Treated Pew’s 2015 2050 projection as an older scenario because Pew revised its 2010 baseline in 2025.
  7. Checked Pew material on U.S. Jewish connections with Israel, Pew Israel-Hamas war surveys, and PRRI U.S. religious population estimates to define the Judaism-evangelical linkage.
  8. Checked Pew U.S. opinion, Pew 36-country Israel favorability, and Pew Israeli domestic opinion to separate Palestinians, the Palestinian Authority, Hamas, and the Israeli government’s military conduct.

Decisions

  • The article was reorganized around global ranking, major-religion country tables, denomination and branch context, country-level diversity, projection limits, and measurement limits.
  • The article does not create a world denominational table because subgroup sources use different years and scopes.
  • Smaller religions are handled through both Pew’s combined “other religions” country table and named India counts for Sikhs, Jains, and Buddhists.
  • Judaism and evangelical Protestantism are connected only where the U.S. pro-Israel political coalition is the topic.
  • Views of Palestine are not reduced to one world opinion because U.S., non-U.S., Israeli, and Palestinian-institution views use different objects and axes.
  • The English article mirrors the Japanese public article with the same table structure and source notes.

Remaining Review Points

  • Denomination and branch data do not share a 2020 baseline, so human review should check that readers cannot confuse country counts with subgroup estimates.
  • Israel-Palestine opinion is fast-moving, so reuse should treat the cited polling as verified on July 2, 2026.
  • If Pew publishes or updates a machine-readable 2025 country dataset, the PDF-extracted country tables can be rechecked.