The Hittites originally tended to worship a local god, and their prayers were primarily directed at securing favorable weather to ensure a good harvest. As the empire became unified, a centralized form of religion developed, incorporating a large number of deities. As chief priest, it became the duty of the king to travel around the country and preside over important religious festivals. It was believed that if a king neglected this duty, perhaps because he was away on a military campaign, the gods would become angry and the state would suffer. Mursilis II was noted for his pious observance of his priestly duties, and several of his prayers have survived. In one prayer, he begged the gods to intercede to save people from a dreadful plague that was ravaging the nation.
Archives found at Hattushash give many details about the large pantheon of deities worshipped in the Old Hittite period, together with descriptions of the ceremonies and hymns of the various religious cults. Texts relating ancient myths also clarify the complex nature of the cults, some of which seem to have been derived and adapted from other cultures. A common theme in many of the myths is one of order and chaos, and the related battles of the gods.
Many myths of the Old Hittite period feature storm gods and sun deities.
Some myths appear to have been derived from older traditional Hatti ones. One story tells of a battle between a storm god and the serpent monster Illuyanka. In the later empire period, other myths were adopted from the conquered Hurrians. Some stories involved Teshup, the storm god, who was to become the head of the Hittite pantheon of deities. Teshup was often accompanied by his consort Arinna, the sun goddess. A powerful rival of Teshup was Kumarbi, the god of grain and the harvest. Some deities were also adopted from the Mesopotamian and Syrian religions, including Ishtar, the goddess of war, who was called Shauska by the Hittites.