Debates over how to classify ancestor reverence often begin with the question of what counts as “religion” at all. When religion is defined in a narrow, Western-derived way—centering on belief in a transcendent deity, formal institutions, and codified doctrines—ancestor rites can appear to fall outside the category. Yet when scholars adopt broader understandings that emphasize systems of symbols, ritual engagement with invisible beings, and the shaping of moral life and existential concerns, ancestor veneration readily appears as a religious phenomenon. This tension reveals how much turns on the definition itself, and how easily a shift in conceptual lens can move ancestor practices from the margins to the center of religious discourse.

Another axis of debate concerns whether these practices are best understood as religion or as cultural custom, ethics, or family duty. In many East and Southeast Asian settings, participants describe what they do in terms of ritual propriety, filial piety, or social obligation, rather than as “worship” in a doctrinal sense. Some scholars therefore emphasize the social and familial functions—maintaining lineage, cohesion, and moral order—while others point to offerings, altars, and beliefs about the ongoing presence and influence of the dead as clear signs of religious meaning. The distinction between “worship” and “veneration” also surfaces here: for some, these rites are about honoring and maintaining relationships rather than supplicating deities, which complicates any simple classification.

A further set of discussions focuses on the boundary between institutional religion and popular or domestic practice. Ancestor rites often unfold at household altars or lineage halls rather than in large temples with formal clergy, which challenges models that equate religion with centralized institutions and canonical texts. Some scholars therefore speak of “household religion” or “domestic cult,” while others argue that the regularity, symbolism, and authority of these rites give them a religious character even without a centralized organization. The fact that many practitioners engage in such rituals out of habit, social expectation, or “just in case,” rather than from elaborated doctrinal belief, raises additional questions about whether belief or practice should be primary in classification.

Finally, the pervasive intertwining of ancestor reverence with Buddhism, Confucianism, Daoism, Shinto, and other local cults makes the boundaries even more porous. In many contexts, the same altar may be shared by ancestors and other spiritual beings, and ancestor rites function as one strand within a wider fabric of spirit and deity cults. Some scholars therefore treat ancestor veneration as a sub-component of broader religious systems or as a cultural substrate that blends with them, while others see it as a cross-cutting institution that transcends any single tradition. Underneath these debates lies a deeper unease about imposing universal categories on practices that have long understood themselves in their own terms, reminding observers that how something is named can shape not only academic analysis but also social and political recognition.