Either a Fallen Angel according to Milton, or some rather vague Adversary according to the Torah. 
If the Angels constitute the Board of Directors, perhaps the Devil and his minions are Human Resources.
Here’s an interesting article on the topic, though he doesn’t seem to cite sources…
Diogenes alrady answered, but just to echo him.
Archaelogy mostly. You can try reading the following works which document the transition of the Jews from pantheon to monotheism, and the transition of Yawheh from a storm god to The Creator of Everything.
The Bible mentions her, but does not give her legitimacy. However, Asherah poles have been found dating to the 6th centure BCE in digs of ancient Jewish villages. The Tanakh (Old Testament), as a reference point, is made from books ranging from the age of 950 BCE to 450 BCE. The Bible does say, though, that King Manasseh placed an Asherah Pole next to The Temple. This would have been sometime between 687 and 642 BCE. Moses on the mountain–i.e. where God commands that there are no other gods besides himself–could have happened no later than 850 BCE (the oldest reference to Moses) and is generally said to have happened sometime between 1450 BCE and 1200 BCE. So theoretically there was at least about 600 years after God revealed himself to the Jewish people, performing lots of grandscale miracles before them, and said, “There can be only one! No worshiping idols!”, that the Jewish people continued to set up Asherah Poles, even the king himself.
Really any other supernatural entity that has eternal life and unatural powers could be classified as a pagan god. And it seems obvious to me that the denial of other pagan gods is what the whole, “no other gods before me” line is all about. But, I understand that many people think that angels are not other gods and that the Devil is a fallen angel, therefore the Devil is not another god. . . but, I don’t buy that.
There’s also Deuteronomy 7:16, variously translated;
“And you shall consume all the peoples that the LORD your God will give over to you. Your eye shall not pity them, neither shall you serve their gods, for that would be a snare to you.”
I learn much from this thread-- ‘henotheism’: great word I was not aware of. Glad to match concepts with words. Diogenes, Polycarp, Schindler, Sage Rat, especially-- great posts, the reason I luv teh Dope.
Obviously Elohim refers to the alien race that built our civilization and gave us guidance. They’re plural but their work is collective and unison. Like duh.
But on the other hand, there are some pretty blatantly contradictory passages in the Bible. There are two creation stories in the first two chapters of Genesis, immediately after each other, which don’t really agree on any particular and actually contradict each other on several points. There are other fairly visible “seams” in Genesis, where at least two or three different sources were stitched together to form the text.
(Not so much a disagreement about the specific issue raised about the verbs and pronouns as it is a caution about that particular “Well, they surely would have noticed a problem as obvious as that” line of argument".)
Yea but he dumped her after she gave him the Meta-virus:)