Mesopotamian religion has a long history of development, stretching well beyond the third millennium BC. Its roots lie in the prehistory of Sumerian civilization, before the invention of writing or the formation of city-states. Before being crowded into a dense urban environment with its unique set of protocols and hazards, the early Sumerians lived in diffuse village communities. They encountered nature on a more basic and immediate level. Hence it is no surprise that their theology and religious practices acquired a naturalistic character. The earliest Sumerian pantheon included gods for the sun, moon, sky, and earth, as well as a number of chthonic deities associated with growth and snakes (Wiggermann, pg. 1867). The deities lacked anthropomorphic features, and did not fit into a clear hierarchy of authority.
Once the Sumerians developed a culture centered around the city-state, however, the character of their religion changed. The prehistoric gods acquired human characteristics, including gender and propitiatory epithets. The surviving prehistoric gods were:
Utu, the sun god, Nanna, the moon goddess, An, the sky god, Inanna, the sky goddess, Enki, the earth god, Enlil, the 'Ether' god, Ninhursag, the lady of the Hills, Ninazu, the lord of healing, Ningishzida, the lord of the True Tree,
(Taken from Wiggermann, pg. 1867).
Towards the end of the third millennium, many of these deities were equated with their Semitic counterparts. Thus Utu corresponded to Shamash, Nanna to Sin, and Enki to Ea.
The most important feature of Sumerian religion at this time was how it co-developed with the emerging political structure of the city-state. In the Uruk period, each city was centered around a large temple dedicated to its patron god or goddess. The temple dominated civic life in that in required a large bureaucracy to oversee daily rituals as well as a great amount of land to supply the frequent sacrifices. It had a special chamber set aside for the god's residence as well as living quarters for temple staff. It eventually acquired the accoutrements associated with the king's palace, such as special quarters for the god's consort and family, and a courtyard for greeting and cleansing visitors (Wiggermann, pg. 1861). The city temple was truly the patron god's 'home' in that it usually had a special room containing a statue which represented the god on earth. Temple functionaries placed food or gifts before the statue both as a form of tribute and as nourishment for the god. Sometimes the elites could place statues of themselves in the god's private chamber along with food and drink, as a more direct means of supplication. (Wiggermann, pg. 1863).
Indeed, in the early Sumerian city-states it was difficult to distinguish secular authority from religious authority, as the temple dominated both religious and civic functions. A city's patron god was symbolically 'married' to the city's chosen leader the EN, who originally held both civic and religious functions as head of state and of the city's main temple. At the beginning of each spring the city ruler would offer ceremonious 'first fruits' of the harvest to the patron god as a sign of his good stewardship, in return for which the god would promise a prosperous ensuing year. In addition, the god was usually accompanied by divine 'ministers' who served as intercessors to ordinary people, much as the human rulers had their own political subordinates. Suppliants to a god often addressed their prayers to these ministers rather than to the god directly.
Although the Sumerian city-states all had local deities, there were also regional cults or special centers whose significance spread to the surrounding cities. The most notable such center was Nippur, a city elevated to great religious importance by the northern king Enmebaragesi in the middle of the third millennium. To unify his realm and solidify his power, Enmebaragesi transformed the temple of Enlil into a national cult, and made Enlil his patron deity (Wiggermann, pg. 1869). Enlil subsequently became the god who installed the rulers of Middle Babylon into their office (von Soden, pg. 64).
Another example of a regional cult comes from Marduk at Babylon. Before the rise of Hammurabi, Marduk played a minor role in the southern Mesopotamian pantheon. As Babylonia grew in political importance, however, Marduk came to the foreground and his new status was cemented in history with the composition of the
a Babylonian creation epic which traces the rise of Marduk to the head of the gods and his conquest of the old chthonic deities.
Although the most visible aspect of Mesopotamian religion was the temple cult, religion also flowed out into the more private aspects of society.
Mesopotamians maintained strong connections in their family, even after death. They believed that the spirit of a deceased family member maintained ties with the living world, and needed its family's support in the afterlife. Thus, just as people periodically made offerings to local gods as a sign of respect and propitiation, they would also make offerings to their departed ancestors, who were often buried underneath the house. Starting from the Ur III period onwards, some elites incorporated 'family chapels' in a special wing of the house dedicated to ancestor worship (Crawford, pg. 121). The sophistication of these chapels ranged from simple inhumations with tools or dishes to including a 'feeding tube' from the surface down into the crypt in order to facilitate regular feedings for the deceased.
With that said, the Mesopotamians believed that if family spirits were not buried, fed, revered appropriately, they could pursue the family and cause them evil. This explains the Mesopotamians' concern for proper burial of the dead, along with their belief that personal misfortune often stemmed from a lack of propitiating a certain family spirit or god.
If the Mesopotamians could be said to have developed a natural science, it would be the science of divination. The Mesopotamians understood divination to be an empirical, rational effort to correlate divinely ordained causes with earthly effects. Rarely was it mystical or shamanistic in nature. The Mesopotamians produced extensive catalogues recording unusual phenomena and the significant consequences they believed were caused by them. They phrased these observations in the form of predictions, the most common form being: 'If X is the case, then Y will happen." For instance, one text states that "If a man has a flushed face and his right eye sticks out, he will be devoured by dogs far from his house." (CT 28, pl. 28 Apud Bottero pg. 127).
There are two noteworthy qualities in these divination texts. The first is the apparent capriciousness or illogicality of many of the predictions. Often the prediction was based on the observation of two real consecutive events, whose causal relationship needed no further empirical validation beyond the fact that both evens were unusual. Sometimes the predictions did have a line of reasoning behind them, which has since become obscure to us. Take, for instance, the following omen based on an animal liver: "If on the right side of the liver there are two finger-shaped outgrowths, it is the omen of a period of Anarchy." Jean Bottero believes this omen comes from the end of the Akkadian period, and refers to the dynastic struggle that occurred around 2195 B.C. The 'two finger-shaped outgrowths' on the liver is meant to be an allusion to a rivalry between competitors for the throne. (Bottero, pg. 132)
The other, more remarkable fact of Mesopotamian divination is its utter comprehensiveness. One of the most famous artifacts from Mari is a clay model of a sheep liver, completely inscribed with cuneiform indicating how to interpret countless features on the organ. (See below)
Sometimes the Mesopotamians even considered events that could only occur in the imagination. For instance, one divinatory text refers to omens concerning the number of gall bladders attached to an animal liver. The text starts with two gall bladders, but then proceeds to consider three, four, and all the way up to seven gall bladders in an animal (Bottero pg. 134). Another text deals with the number of children a woman gives birth to at a single time, starting with twins but going all the way to nonuplets (Bottero, pg. 135). It is certain that the Mesopotamians had never observed an animal with seven gall bladders or a nonuplet, but that does not mean they considered it impossible. Unlike modern science, Mesopotamian divination was not oriented toward the concept of immutable laws of nature. It instead concerned itself with portents, or unusual deviations from the regular order of things. Omens were signs from the gods of more significant phenomena, and because the gods were masters of the world they could certainly produce any sign conceivable by man.
The Mesopotamians believed it was possible in certain instances to transfer evil or divine wrath from one subject onto a substitute. This was particularly true with curses or disease. Various texts refer to rituals where a person could transfer his illness onto a clay figurine or a live animal. Usually the substitute had to be in close proximity to the afflicted person or be symbolically invested with his identity in order to work.
The most unusual and fascinating example of substitution is the concept of the 'substitute king'. The idea seems to have been most prevalent in the Neo-Assyrian period, although traces of it appear earlier. Occasionally a disasterous omen such as a solar eclipse occured that foretold ill fortune for the head of state. In order to avert the harm to the king, royal diviners would select a relatively unimportant individual from the people and temporarily install him as ruler. Although this installation was completely fictitious in that the substitute had no authority, he was given every means to appear so. He sat on the king's throne, wore his clothes and regalia, and was even given a woman to act as his queen (Bottero, pg. 150). The real king would retreat to a place of safety. After a set time (Bottero suggests about 100 days, pg. 148), the king would return and the substitute along with his temporary wife would be killed.
In many cities, the statues of the chief gods were taken into the streets once a year for public display. Much as a king might make the rounds in his domain, the city gods were carried on litters in a festive parade through the streets. The most famous parade occurred at the New Year Festival in Babylon. There, the statue of Marduk was taken from his great temple out to a special house outside the city walls, while people recited the Creation Epic to honor him. Sometimes the gods could even make peregrinations between cities, as was the case with Nabu of Borsippa, whose statue made yearly treks out to Babylon to 'visit' his father Marduk (von Soden, pg. 191).