Welcome.
None of the above.
In order to understand the Temple of Zeus, the important aspect is to go all the way back and don't attempt to draw parelels. Gnosticism is Christianity confused with Neoplatonism.
The "Great Battle" is a cosmological motif; such as the Titanomachy. It's a symbolic battle, not a real one, between the pure and the impure elements of creation [it exists in all Ancient Religions of the Gods, such as the battle between the Gods and the Asuras].
Titanomachy will be updated. In the context of Gnosticism, the "Demiurge" comes from the Ancient Greek "Δημιουργός" which means an opposer of "God" insofar this opposer is "Creating" the world. However, because Gnosticism was life hating and nature hating, it started to blend this concept over with the concept that creation itself was evil; but without the Demiurge to create a world [a defined world, versus "God" or the Eternal Light in which there is nothing else] there would be no world.
I'd advise to keep your knowledge of Gnosticism and proceed in understanding deeper via Zevism.