The Gaddang people are an ethnic group in Philippine that has a unique set of religious beliefs and practices. In their traditional religion, the concept of Nanolay, a deity that is both the creator of all things and a culture hero, is prominent. Other deities include Dasal, who is prayed to before going into battle, and the fathers of two heroes that are Bunag, the god of the earth, and Limat, the god of the sea. 

Gaddang cosmology includes dufafa, which is the material world, and kalekay, the afterlife. In Gaddang cosmogony, the term describes the place where all living things originated, the place where Nanolay performed his acts of creation. The Gaddang have a paranoidal fear of danger due to a history of headhunting and present times ridden with disease and malnutrition. 

According to the Gaddang, the earth is made up of "man, domesticated plants, ghouls, illness, and all," and they believe in two kinds of illness. Most illness is attributed to natural causes, although they also believe that illness can be caused by evil spirits, like the bingil and aran. The Gaddang have several kinds of medium, such as the mengal and mabayan, and they perform anitu rites and other rituals related to planting, harvesting, death, warfare, sickness, or misfortune. Anitu does not refer to an ancestral spirit, but a supernatural power, and it is understood as that which is followed by all. Gaddang have an anitu rite of seven rites of passage, which can be used to cure the sick and avoid misfortune due to breach of a taboo.

The Gaddang have a complex social system built upon shared kinship, which has emerged as a means of organizing their society in the absence of a formal political structure. During their pre-Conquest history, their swidden economy and small population scattered over a large area forced them to rely on kinship to maintain ties between settlements. Given the repeated conflicts and head-taking that characterized pre-Conquest times, kinship obligations became the essential means of linking settlements and ensuring their security. Additionally, certain kin-links like temporary marriage have no modern counterparts.

Similar to other Indo-Malay cultures, Gaddang kinship relationships are highly intricate and feature a wide range of prestige markers based on personal accomplishment and social obligations that often span generations. Although language makes no differentiation beyond second-degree consanguinity, there is a great deal of importance placed on tracing common lineal descent in the Gaddang culture. Relationships can be traced through both patrilineal and matrilineal descent and may also include compadre/co-madre lines as well as mentorship ties.

The extent to which mailan and other remnants of the slavery system have influenced the Gaddang kinship system is unclear. 

Christian Gaddang funerals in modern times generally involve entombment in a public or private cemetery after a celebration of Mass and a procession with a band (if available). The wake usually lasts several days, providing family and friends with ample time to travel and visit the deceased in the coffin. Mummification practices are not commonly observed, but cremation followed by entombment of the ashes has been noted. 

The Gaddang mythology includes a variety of deities:

Nanolay – Is both creator of all things and a cultural hero. In the latter role, he is a beneficent deity. Nanolay is described in myth as a fully benevolent deity, never inflicting pain or punishment on the people. He is responsible for the origin and development of the world.

Ofag – Nanolay's cousin.

Dasal – To whom the epic warriors Biwag and Malana prayed for strength and courage before going off to their final battle.

Bunag – The god of the earth.

Limat – The god of the sea.