Sumerian theology

In Sumerian theology, the Sumerians credited their divinities for all matters pertaining to them and exhibited humility in the face of cosmic forces, such as death and divine wrath. Sumerian theology seems to have been founded upon two separate cosmogenic myths. The first saw creation as the result of a series of hieroi gamoi or sacred marriages, involving the reconciliation of opposites, postulated as a coming together of male and female divine beings; the gods. This continued to influence the whole Mesopotamian mythos. Thus, in the later Akkadian Enuma Elish, the creation was seen as the union of fresh and salt water; as male Abzu, and female Tiamat. The products of that union, Lahm and Lahmu, "the muddy ones", were titles given to the gate keepers of the E-Abzu temple of Enkik, in Eridu, the first Sumerian city. Describing the way that muddy islands emerge from the confluence of fresh and salty water at the mouth of the Euphrates, where the river deposited its load of silt, a second hieros gamos supposedly created Anshar and Kishar, the "sky-pivot" or axle, and the "earth pivot", parents in turn of Anu (the sky) and Ki (the earth). Another important Sumerian hieros gamos was that between Ki, here known as Ninhursag or "Lady of the Mountains", and Enki of Eridu, the god of fresh water which brought forth greenery and pasture.

Cosmology
Sumerians believed that the universe consisted of a flat disk enclosed by a dome. The Sumerian afterlife involved a descent into a gloomy netherworld to spend eternity in a wretched existence as a Gidim (ghost).

The universe was divided into four quarters:
 * To the north were the hill-dwelling Subartu, who were periodically raided for slaves, timber, and other raw materials.
 * To the west were the tent-dwelling Martu, ancient Semitic-speaking peoples living as pastoral nomads tending herds of sheep and goats.
 * To the south was the land of Dilmun, a trading state associated with the land of the dead and the place of creation.
 * To the east were the Elamites, a rival people with whom the Sumerians were frequently at war.

Their known world extended from The Upper Sea or Mediterranean coastline, to The Lower Sea, the Persian Gulf and the land of Meluhha (probably the Indus Valley) and Magan (Oman), famed for its copper ores.

Temple cities
Sumerian deities were associated with different cities, and their religious importance often waxed and waned with those cities' political power. The gods were said to have created human beings from clay for the purpose of serving them. The temples organized the mass labour projects needed for irrigation agriculture. Citizens had a labor duty to the temple, though they could avoid it by a payment of silver.

At an early stage, following the dawn of recorded history, Nippur, in central Mesopotamia, replaced Eridu in the south as the primary temple city, whose priests exercised political hegemony on the other city-states. Nippur retained this status throughout the Sumerian period.

Sumerians believed in an anthropomorphic polytheism, or the belief in many gods in human form. There was no common set of gods; each city-state had its own patrons, temples, and priest-kings. Nonetheless, these were not exclusive; the gods of one city were often acknowledged elsewhere. Sumerian speakers were among the earliest people to record their beliefs in writing, and were a major inspiration in later Mesopotamian mythology, religion, and astrology.
 * Deities

The Sumerians deified:
 * An as the full-time god equivalent to heaven; indeed, the word an in Sumerian means sky and his consort Ki, means earth.
 * Enki in the south at the temple in Eridu. Enki was the god of beneficence and of wisdom, ruler of the freshwater depths beneath the earth, a healer and friend to humanity who in Sumerian myth was thought to have given humans the arts and sciences, the industries and manners of civilization; the first law book was considered his creation,
 * Enlil was the god of storm, wind, and rain. He was the chief god of the Sumerian pantheon   and the patron god of Nippur.  His consort was Ninlil, the goddess of the south wind.
 * Inanna was the goddess of love, beauty, sexuality, prostitution, and war;  the deification of Venus, the morning (eastern) and evening (western) star, at the temple (shared with An) at Uruk. Deified kings may have re-enacted the marriage of Inanna and Dumuzid with priestesses.
 * The sun-god Utu at Larsa in the south and Sippar in the north,
 * The moon god Sin at Ur.

Temples
Sumerian temples, known as Ziggurats, each had an individual name and consisted of a forecourt, with a central pond for purification. The temple itself had a central nave with aisles along either side. Flanking the aisles would be rooms for the priests. At one end would stand the podium and a mudbrick table for animal and vegetable sacrifices. Granaries and storehouses were usually located near the temples. After a time the Sumerians began to place the temples on top of multi-layered square constructions built as a series of rising terraces, giving rise to the Ziggurat style.

Funerary practices
It was believed that when people died, they would be confined to a gloomy world of Ereshkigal, whose realm was guarded by gateways with various monsters designed to prevent people entering or leaving. The dead were buried outside the city walls in graveyards where a small mound covered the corpse, along with offerings to monsters and a small amount of food. Those who could afford it sought burial at Dilmun. Human sacrifice was found in the death pits at the Ur royal cemetery where Queen Puabi was accompanied in death by her servants.