The Ancient Hawaiian Religion is based on a couple things:

The Kapu ... A system which was grounded upon many restrictions, which kept the common people in obedience.

Aumakua Worship ... The worship of Ancestral gods.

An old Hawaiian belief is that in Ancient times, the gods came to Hawaii from overseas with their families and follwers and peopled the Islands. Up to that  time only spirits lived there. For a long time, they lived with their people as visible, personal gods. When the people began to live their lives in an evil way, the gods left them and went elsewhere. The Hawaiians believed that the spirits of the dead continued to hover around their homes and the shades of their ancestors were appealed to in prayer.