Preemptive follow up/sidejack question; I was introduced to Sumerian mythology through Neal Stephenson's Snow Crash. How accurate is Stephenson's depiction?

To itsallfolklore, just wondering, but what does one of the ancient cities of Mesopotamia (Ur) have to do with anything? If anything, the idea being pushed by your friend is that the pantheon system (system of gods/goddesses) used by the Sumerians is shared between multiple, ancient cultures and supposedly extends it's influence into old-world paganism.

With a quick Google search we can find out that the pantheon system of the Sumerian culture is extensive, with the most prominent figures being: Anu, Enlil, Enki, Marduk, Ninmah, and Inanna, however the general list does not end here. The next logical step would be to check whether any of these gods/goddesses make an appearance in other ancient cultures around the world that can be considered pagan. This again, can be checked via another quick google search, which reveals that the Greeks, Levantines, Mesopotamian, and Egyptians did include these six deities (among others) as beings of importance in their individual pantheons, of course under different aliases, all of which can also be discovered via Google (Isn't the internet wonderful?).

Because you're specifically asking about the Deity, Enki, I will list all known aliases that you can go dig up using the internet that pertain to these cultures. Enki = Ea, Ptah, Shiva, Prometheus, Odin, Krishna, Nataraja, Rudra, Neptune, and Poseidon. (Iv'e been told the list doesn't end here, but I have yet to find sources for other alternative names so I will not list them)

So now that the association can be made between these four cultures that mark the early beginning eras of recorded, civilized man and religion/spirituality/whatever, we can then attempt to figure out if this pantheon system has had any influence or revival in any of the prominent old-world forms of paganism. With a quick google search we can find that Enki and his brother/superior (depending on which culture's perspective/mythology you're looking into) make their reappearances in Celtic, Slavic, and Graeco-Roman paganism, along with a large proportion of the rest of the Sumerian Pantheon.

So in short, your friend is correct, ancient paganism as practiced by these cultures did share Enki (Along with others) as a deity in their separate pantheon systems. However, there's a lot more to it, each culture placing a different one of these Deities in a position of overall superiority in their pantheon, but I will not get into that.

Paganism has multiple agreed upon definitions because it is such a broad term, with many sub-religions based upon it, some that ignore key practices/ideas in paganism altogether. But if we scale it back and look at it from a bare bones perspective: Old-world paganism or classical paganism is any spiritual belief that encompasses what pagans call "The Old Gods" aka the deities mentioned above and others, along with spiritual beliefs that exercise the use of any occult knowledge supposedly given unto the human species by these "Old Gods." Some modern forms of paganism strive to capture the essence of "Old-world" paganism, even including the old world pantheons. But in all honesty, this is a question that belongs in a subject mix between Religious history, Archaeology, and Ancient World History. Without extensively relying on all three fields of study you will quickly run into dead-ends, disinformation, or simply erroneous information and haste conclusions.

For Translators willing to do a little work to further their knowledge: http://digitalcollections.tcd.ie/home/index.php?DRIS_ID=MS58_003v https://www.escholar.manchester.ac.uk/api/datastream?publicationPid=uk-ac-man-scw:4o973&datastreamId=FULL-TEXT.PDF