The Sediq people believe in supernaturalism, with utux (ancestral spirits) being the most important belief. Believing that ancestral spirits will affect fortune and misfortune in daily life, Sediq people strictly follow gaya, (the ancestral rules and code of conduct). Therefore, worshipping ancestral spirits is very important to them. After accepting Western religions in the 1960s, mostly Christianity, Sediq people have stopped almost all traditional rituals and ceremonies. With the rise of cultural awareness in recent years, some Sediq communitiess have resumed the ritual of ancestral spirits.
To the Sediq people, ancestral spirits and gaya (ancestral rules) are very important. Such a culture is also reflected in the annual rituals and ceremonies. In rituals and ceremonies relating to agriculture and hunting, thanksgiving for ancestral spirits is an important part. Apart from worshipping ancestral spirits privately, the Sediq people also worship ancestral spirits in the community. The Ancestral Spirit Ritual is held after the millet harvest, and the actual time is determined by the chief or elders after discussions. When presenting offerings including wine, millet rice cakes, crops, fruit, and fish, the Sediq people tie them on bamboo, and elders call the ancestral spirits to consume them. After the ritual, they eat all offerings onsite. When leaving the ritual venue, they leave food waste onsite and cross over the fire to symbolize separation from the ancestral spirits. On the way home, they do not look back. The Ancestral Spirit Ritual was banned during Japanese colonization and has been held again in recent years.