The slaying of a goddess to create the material world
This story is centered around a religious allegory which heralds the fire god for killing the oceanic goddess. This is a metaphor for order being born from disorder, establishing systems and natural forces that allow this reality to exist. The allegory also involves the destruction of a serpent, which has moralistic implications in the near-eastern world.
Lightning as the creator's force
The god who is responsible for the creation of the world is Marduk, and the manner by which he rises to power is by electrifying the waters of the great sea serpent, Tiamat. This is a symbolic representation of energy creating life from nothing. In the Sumerian world, fire is the element responsible for reality. (They understood lightning to be a fiery device.
The allegory of the throne
Before Marduk agrees to work on behalf of the pantheon, he proclaims that if he wins over Tiamat, that means his 'fate is preeminent.' That is to say, that if he kills Tiamat, who is struggling for the throne of heaven, that he himself gets to be the king.
This religious allegory understands each god to be elemental, meaning that the current reality of the universe would be a representation of the elemental forces of the god who rules over heaven. It's an explanation of the natural forces and the supernatural cosmology of their faith, using the gods as metaphorical characters in a representational narrative. (This doesn't mean they didn't think they were also real; they did believe the texts to be literally true, and they worshiped their gods).
The expanse between the sky and waters and Tiamat's body
The text uses the body of Tiamat (who is watery) to explain why the sky is blue and why there is space between the waters of heaven (the sky waters) and the earthly waters. The explanation is offered in allegorical form, when Marduk slices Tiamat's body in half, leaving one half to be the waters of the earth, and essentially stapling the other half into the ceiling, using lightning as his staples. This is also an explanation for weather. In the fight between Marduk and Tiamat, Marduk creates the four winds, and in the aftermath, the winds interact with the fallen body of Tiamat to create the weather cycles. He also fashions the stars into heaven, which the Sumerians would have understood to also affect the weather.
Morality is an extension of the will of the gods
One major difference between the Abrahamic religions and the Sumerian religions is their view of morality. In the Sumerian account, the gods are capricious, contentious forces who are add odds with one another. So, the moralistic value of the allegory is radically different than the modern understanding of 'good and evil.' Good is to align oneself with the gods who have power in heaven through devotion, worship and obedience.
