“He divided the monstrous shape and created marvels (from it).
He sliced her in half like a fish for drying:
Half of her he put up to the roof of the sky,
Drew a bolt across and made a guard hold it.
Her waters he arranged so that they could not escape.” (The Epic of Creation, 255)
The Mother-Goddess Tiamat is serving multiple purposes here. FIrst (though in no particular order), she is a metonymy for the ocean, an emanation / pathogenesis, “And maker Tiamat, who bore them all,” (233) of life, which Marduk cuts in half (like Moses will later in another Semitic text, the Hebrew Bible), but she is also a source of fertility / nourishment (a fish) from which Marduk will create the world (cosmogony) from.
Second, she is part of the older generation which Marduk battles against (theomachy) and succeeds in overthrowing and securing his position of power when he takes the Tablet of Destinies, “Wrested from him the Tablet of Destinies,” (254) which cements his fate as the supreme ruler (Sky-God) and establishes his pattern for celestial hierophany (the heavenly sacred order).
This overthrow is also significant because since Marduk is male and Tiamat is female we have a fiction (mythos) explaining how the patriarchy has wrestled power away from the matriarchy. Tiamat, like the Ginnungagap, is a mixture of two forms. Here this mixture is of the waters, the fresh (as represented by the progenitor God Apsu) and the salt waters. Fertile Tiamat had been the goddess who the successive gods, such as Marduk, emanated from (like Aditi is in the Rig Veda), but now Marduk in his bid for power seeks to gain this power of creation for himself and whom the other gods have given him commission to do so, “We hereby give you sovereignty over all of the whole universe,” (250) and, “They gave him an unfaceable weapon [the winds] to crush the foe,” (250). Tiamat’s mysterious female powers of creation (the fertile waters) are now under Marduk’s (a male’s) complete control, “LUGAL-DIMMER-ANKIA is his name. Trust in him!” (259). Marduk, the Bull-Calf of the Sun is the new, masculine Warrior-Sky-God.
One other point to address is that, like Zeus later, Marduk, a male, has taken on the previously feminine role of birth and creation. The second generation of Gods emanated from Tiamat, but now the world and all subsequent generations can be brought into existence through the violent effort of the dominant male. What had once been a mysterious emanation that can’t be easily explained, can now quantified through Marduk’s actions with Taimat’s corpse.
Third we have the cosmogony where after having killed off the old generation (overthrow), the new world can be created according to Marduk’s plan. Marduk, now the God-Sky-King creates the world through the corpse of the Proto-Godess, Tiamat. And from this cosmogony, man – a slave race – is created from the blood of Qingu (blood anthropogony), “He created mankind from his blood,” (261).
All-in-all, this myth justifies Marduk’s violence. Tiamat originally was willing to show compassion (a female trait), “Even though their ways are grievous, we should bear it patiently,” (234) towards the younger generation for causing trouble and for killing the progenitor god, Apsu. Yet Marduk does not need compassion, he is a violent male, yet he still has to justify his violent actions and this mythos explains / justifies how and why Marduk slew Tiamat to create the world we now (as Babylonians, anyway) are slaves in and worshipers of the Sky-God, Marduk.