Partly restricted: some elements are closed to outsiders

This category holds the world's organised religious traditions, from the largest to those of historical importance that are no longer practised, together with the non-theistic worldviews (atheism, agnosticism, deism, secular humanism), since these answer the same fundamental questions in their own way and are studied alongside religions in the academic field.

A religion, as used here, is a whole tradition with its own account of the sacred, its scriptures or foundational teachings, its practices and community. The entries describe each in its own terms, note its size and distribution where relevant, and distinguish confessional self-description from the findings of the historical and social study of religion.

Scholars classify religions in several overlapping ways, by descent (Abrahamic, Dharmic), by structure (monotheistic, polytheistic, non-theistic), by scope (universal, ethnic), and no single scheme is definitive. The atlas records the classifications that are useful for orientation while treating them as maps, not essences, and the religion entries group by such families so a browser can move from all traditions to one family.

Every religion contains internal diversity, and its branches, schools and movements are treated as denominations; the practices, festivals, scriptures and figures of a tradition are found under their own categories throughout the atlas.