TL;DR
The label 'religion' as we use it is a relatively recent intellectual invention rather than an ancient category. Scholars across disciplines have proposed many competing definitions, none of which capture every tradition without excluding or overextending, yet the term continues to shape study and comparison of belief systems.
What happened
Kwame Anthony Appiah traces the history and persistent ambiguity of the term 'religion'. He shows that although practices like gods, rituals and temples are ancient, the specific category 'religion' emerged in the early modern period. Roman vocabularies used related words—such as religio, cultus and ritus—but did not classify disparate local practices as instances of a single genus. The modern comparative sense of religion appears in 17th-century European thought, intensified by intra-Christian disputes and encounters with non-European cultures. From the 19th century onward, academics attempted systematic definitions—focusing variously on belief, ritual, social function, symbolic systems or evolutionary origins—but each proposal proved limited. Appiah surveys influential figures (Mill, Spencer, Tylor, Max Müller, Robertson Smith, Durkheim, Geertz and others), arguing that efforts to pin down a single definition repeatedly either exclude important cases or sweep too broadly, yet the category remains indispensable for scholarship and public discourse.
Why it matters
- How we define 'religion' shapes academic comparison and may impose Western templates on diverse traditions.
- Classification affects what practices and texts are treated as authoritative or central within a tradition.
- Ambiguity in the term influences disciplines differently—history, anthropology, sociology and theology reach different priorities.
- Despite its vagueness, 'religion' remains a necessary analytic category for organizing study and public discussion of belief and practice.
Key facts
- The modern comparative sense of 'religion' developed in the early modern era rather than in antiquity.
- Romans used words like religio, cultus, ritus and superstitio but did not sort foreign practices into a single universal category.
- Scholars point to 17th-century works, such as Hugo Grotius's De veritate religionis Christianae (1627), as milestones in shaping the modern notion.
- European encounters with other cultures and internal Christian divisions pushed thinkers to ask what counted as 'true religion'.
- In the 19th century, academic study produced the notion of 'world religions' by grouping diverse local practices into bounded systems.
- Debates about definition became visible in contested cases such as Buddhism, which challenged scholars to decide inclusion criteria.
- Major thinkers who proposed definitions include John Stuart Mill, Herbert Spencer, E. B. Tylor, Max Müller, William Robertson Smith and Émile Durkheim.
- Later approaches ranged from symbolic and functional accounts (Clifford Geertz, Durkheim’s followers) to evolutionary and cognitive theories (e.g., Robin Dunbar).
- Critics like Georg Simmel and Jane Ellen Harrison warned against expecting a single word or neat definition to capture the phenomenon.
What to watch next
- Ongoing academic debates about how to handle non‑Western and heterogeneous traditions within comparative frameworks.
- How historians and social scientists continue to revise or resist 'world religions' categories when documenting local practices.
- not confirmed in the source
Quick glossary
- religio: A Latin term used by the Romans to denote careful observance, scruple or exactness in duties and rites.
- cultus / ritus / superstitio: Related Latin terms referring to worship practices, ritual forms and beliefs judged excessive or mistaken; used to describe aspects of public and private religious life.
- secular: A sphere of life or inquiry considered separate from religious authority or clerical institutions.
- world religions: A scholarly category that groups large, historically influential traditions into bounded systems for comparison.
- sacred vs profane: A conceptual distinction used in some sociological theories to separate things set apart and treated with reverence from ordinary, everyday matters.
Reader FAQ
Is 'religion' an ancient word with a stable meaning?
No; the specific comparative category 'religion' is a relatively recent development dating to the early modern period, whereas ancient societies used different concepts.
Did the Romans have a concept equivalent to our 'religion'?
They had terms like religio, cultus and ritus, which referred to scrupulous observance and ritual, but they did not treat disparate practices as instances of a single universal category.
Have scholars agreed on a single definition?
No; thinkers from multiple disciplines have proposed competing definitions (belief, ritual, social function, symbols, evolutionary accounts), and each faces counterexamples.
Were 'world religions' always recognized as distinct systems?
No; the idea of treating traditions as bounded 'world religions' was developed in the 19th century as scholarship sought comparative frameworks, often shaping how local practices were represented.

Undefinable yet indispensable Despite centuries of trying, the term ‘religion’ has proven impossible to define. Then why does it remain so necessary? Women give thanks to the Sea-God during the…
Sources
- Undefinable yet Indispensable
- The Concept of Religion – Stanford Encyclopedia of Philosophy
- Why is it difficult to have a universal definition for religion?
- One good way to understand religion is to break it apart
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