The complexity of Ifugao religion is based in part on the complex Ifugao cosmology. The Ifugao divide the universe into the known earth, pugao (the people refer to themselves as "Ipugao," or "inhabitants of the known earth"); the sky world, kabunian ; the underworld, dalum ; the downstream area, lagod ; and the upstream area, daiya. Each of these five regions has large numbers of spirits. The spirits have individual names and each belongs to one of thirty-five categories, among them hero ancestors, celestial bodies, natural phenomena, and diseases. In addition, the Ifugao have deities; these figures are immortal, are able to change form or become invisible, and are mobile.
Ifugao priests are men who take their positions voluntarily and after a period of apprenticeship. Their job is to serve the members of their kindreds by invoking the spirits of deceased ancestors and deities. Priests do not make their living from their priestly activities, although they are compensated with meat, drink, and prestige.
Rituals and ceremonies—for the purposes of augury, omenology, hunting success, agricultural abundance, prestige feasts, etc.—typically make use of as many as fifteen priests. Priests recite myths to give them power over the deities and hero ancestors named in them, by way of inviting them to possess their bodies. Invoking deities may involve chanting for more than five hours. Once in the priest, a deity is given an offering (which may be betel, chicken claw, pig, chicken, etc.) and is fed rice and wine (through the body of the priest). Finally, an exhortation is made to the deity.
Illness is caused by deities taking souls in cooperation with ancestors. Priests treat illness through divination and curing rituals, in an effort to have the deity return the soul. If the deity does not do so, the sick individual dies. A corpse is washed, its orifices are plugged, and it is placed in an honorary death chair (corpses of kadangyan people are given insignias) . There the body lies in state guarded by a fire and a corpse tender, and it is "awakened" each night; the wealthier the deceased, the longer this period lasts (up to thirteen days). Burial is in a family sepulcher or in a coffin that is placed either in a mausoleum or under the house. Sometimes secondary burials take place three to five years later, especially if the deceased is unhappy and causing illness among the living. Some Ifugao groups bury males and females separately and inter children in jars.