Waaqeffanna, the indigenous Oromo religion, addresses a single sky god, Waaqa, whom Lambert Bartels' fieldwork among the western Oromo describes as remote, all seeing and morally demanding rather than approached through a pantheon of lesser gods. Ayyaana, a term covering both personal spirit and cosmic order, links Waaqa's will to the fortune of individuals and clans, and offense against the moral order, safuu, is understood to draw Waaqa's displeasure more than ritual failure does. The qallu, a hereditary ritual specialist distinct from gadaa political office, communicates Waaqa's will and blesses the community, while diviners and rainmakers hold narrower roles.
The best known public rite is Irreecha, a thanksgiving festival held at Lake Hora Harsadi near Bishoftu and at other sites, where Oromo gather in white cloth to thank Waaqa for the harvest and the passing of the rainy season, a rite Waaqeffanna practitioners and many Oromo Muslims and Christians alike still observe as a marker of Oromo identity.
Islam and Ethiopian Orthodox Christianity became the majority faiths of most Oromo from the nineteenth century onward, often absorbing Waaqeffanna vocabulary and practice rather than replacing it outright. Waaqeffanna itself, reduced to a minority faith under imperial and later socialist era pressure, has seen organized revival since the 1990s, with formal associations now seeking legal recognition alongside Ethiopia's older religions.