Household religion is the label historians of religion give to worship practiced inside the home rather than at a temple, a church or any other communal building, addressed to whichever beings a family holds responsible for its safety, its harvest, its childbirths and its dead. It is not a single tradition. It is a pattern that keeps recurring wherever scholars look closely at ordinary domestic life rather than at official institutions, and the standard scholarly treatment, Bodel and Olyan's edited collection Household and Family Religion in Antiquity, argues the ancient Mediterranean and West Asian evidence supports treating it as a category in its own right, not a private copy of state or temple religion.
Roman households kept a shrine called the lararium for the Lares, guardian spirits of the household and its land, and the Penates, guardians of the pantry and its stores, tending them daily alongside the hearth fire. Chinese folk religion keeps a kitchen god, Zao Jun, whose paper image watches the household all year before being sent to heaven each new year to report on the family's conduct, and keeps ancestral tablets on a home altar to receive offerings. Japanese households set a kamidana, a small shelf shrine, to house protective kami. Hindu households perform daily puja before a home shrine, following rules recorded as early as the Grihya Sutras, texts devoted specifically to domestic ceremony. Slavic folk belief keeps a domovoi, a household spirit propitiated to protect the home and warn of misfortune.
What unites these otherwise unrelated traditions is not doctrine but location and audience, a household's own dead, its own hearth and its own threshold, tended by the family itself rather than by professional clergy.