Cool that we managed to connect.
When we talk about these things, I think we are actually dealing with two very different subjects.
1st off, there is the undeniable influence that Sumerian myth, legend, cosmology, and history had on the religions of Abraham. This is not surprising though, or even peculiar to the Abrahamic faiths. The Sumerians cast a long shadow over all things in and around the fertile crescent. Everyone who came after them was influenced by them... even if they didn't know about it. Many people were influenced indirectly 2nd, 3rd, and 4th hand from the other cultures which adopted their stylings. Things like the base 12 mathematics and calendrics rippled out, and show up in cultures thousands of miles away. The reason we have 60 seconds in a minute and 60 minutes in an hour, 24 hour days, and 12 months in a year, 12 inches to a foot etc... All of this comes from Sumer. Most pantheistic religions have 12 major deities, and when one dies or leaves they are always replaced to keep the number at 12, a notion that started with Sumer.
G*D in the Bible is often talking to himself pointlessly, or acting in schizophrenic ways. Going back to the Sumerian versions often reveals a much more coherent and complete story where the confusion is completely dispelled. Kicking the humans out of E-din because they have become too much "like us" and only need to eat of the tree of life to become "as the gods" makes more sense when the speaker is merely the king of the gods talking to an adviser, and not a cosmic unitary figure. The flood, as well, seems much more solid as a story when the god who causes the flood is not the same god as the one who wants to save his favorite creations/offspring in the form of a family of demi-gods... and instead of bringing 2 of every animal onto the ark, the male and female "seeds" of every animal are saved (genetics anyone?). Furthermore, Elohim (a Hebrew word for G*D) actually does mean gods, as all words ending in im are plural.
Religious people tend to balk when they hear of this stuff, and just write these things off out of hand. But the Bible is chalk full of things that people who claim it to be the inerrant word of G*D would ridicule if said by anyone else. The frequent mention of "flaming flying chariots" alone is enough to evoke sci-fi imagery for me. Giants, dragons, human-seeming supermen? This stuff is far out. The fact is, that angels (all 12 varieties mentioned in biblical and apocryphal sources) are ETs. This is not even accepting any theories of Sitchin or Von Danniken (who I met a couple times BTW and was a super cool cat)... The Bible says that angels were created before the Earth. They live somewhere that is not the Earth... therefore, BY DEFINITION, they are "extra terrestrial" (outside of earthly).
This brings us to the 2nd issue. A bit more sticky, but certainly worthy of some analysis. Is Sitchin right? The easy answer is "who knows?" There is no real way to prove or disprove this stuff. It certainly does make certain Bible contradictions make more sense and explains some troubling megaliths around the world. Is Sitchin the pre-eminent scholar on semetic languages that he claims? Hard to say. He certainly has detractors. So does Darwin. Anyway, all theories are just that... theories.
Sitchin has a wealth of convincing data for his position, and even if you could discount 80% of it... it would still be a formidable edifice. Michael Heiser is a very vocal critic, but his arguments tend to be nit-picky and semantic while never really debunking the main premises. Turns out he was promoting his own book of fictionalized non-fiction-ish ponderings called The Façade, and that he believes in aliens and all that jazz... only differently than Sitchin.
While this 2nd aspect is controversial and attention-getting, it is a relatively dead end. All we can really say is that there are tons of myths and legends that claim these things more or less... written by people who didn't practice fiction writing. In those days, if you wrote something down it was because you believed it to be historical truth. There were no Sumerian Isaac Asimovs. Fiction writing as we know it is a relatively modern thing.
It is easy enough to declaim a particular translation of some verb or whatever, but I have yet to see anyone deny the striking similarities in the various myths and legends which Sitchin points out. No credible scholar can now deny that the creation story, the Tower of Babel, The Flood, the Watchers, the Anakim et al weren't borrowed wholesale from what was Abraham's original religion. His father carved idols of Sumerian gods for Pete's sake!
None of this discounts the fresh ideas of monotheism, though. The tendency to translate any number of phrases and words from the Hebrew as G*D is probably the root problem here. "The King who art in heaven" does not necessarily refer to the same being as "The Lord of the Earth." In Sumer the first title belonged to Enlil while the second belonged to Enki. "G*D the Father" may not be the same entity as the "Lord of Hosts" etc. (the half-brothers Enki & Enlil respectively in the Sumerian texts) As Sitchin (a Jew) is fond of saying...
"Just because the elohim were a race of space-faring gods that we call angels, doesn't mean that there is not also a truly omniscient G*D of the Universe. Remember, the gods themselves had gods."
(I say don't get too hung up on any of this stuff. Take everything you read somewhat critically, and don't misplace your sense of humor. ;-)
