…Eventually, “Satan” does become an independent and malevolent force in his own right. In Zechariah 3:1-2, we begin to see the slow separation of Satan from god during an internal Jewish conflict. With time, as the various Jewish communities began to disperse, Satan came to be seen as an entity opposed to both god and Israel . So, as problems affecting the Jewish community grew, so too did the divide between god and the satans, who by this time were well on their way to becoming Satan proper. It seems that the Jewish people simply needed someone to blame ~ and that someone could not be their god. Thus, the evil component of the deity had to be separated and personified as a rival and unrelated force. Ironically, it is the advent of the devil that makes this god wholly good.
Eventually, the figure of Satan emerged out of the initially dual nature of the Hebrew YHWH. The separation of God’s character into two opposing forces is a highly complex subject that spans several centuries and societies, touching on the separation of good and evil in multiple belief systems. Two brief examples outside of Judaism must suffice here. The first clearly dualistic theology can be found in the teachings of Zarathustra, the founder of the Zoroastrian religion. This was the first religion to be explicitly dualist, meaning there was a sharp distinction between good and evil, so much so that it amounted to the equivalent of two opposing gods, though the evil spirit was seen as inferior ,
Much later, we have a pupil of Plato, Xenocrates, often held responsible for philosophically separating good and evil in the cosmos, whereas previously the two polar notions had been inexplicably intertwined in Greek thought , a system which was highly influential on the development of Christianity. Finally, we return to the Septuagint, the translators of which firmly separated evil demons from good angels, erasing their confusing ambiguity . These factors, and countless others, contributed to the evolution of the character of the Hebrew satans into the Christian Satan.
But where did the idea for a malevolent entity come from? The short answer is life experience; bad things happen to good people so there must be someone to blame. The more complicated answer? As for early Judaism, we might look to neighboring gods who worked their way into the texts. Moloch, in particular, is a fine candidate. Yes, that Moloch, the insatiable one to whom the Jew would offer “Holocaust”, meaning burnt offering, meaning their children were sacrificed in the burning belly of the beast (Literally. The statue of the god was a sort of oven). But was Moloch merely a neighboring god? Not exactly. YHWH, the famed four letter name of the Hebrew divinity, was archaically known as Mal’ak Yahweh (Mal’ak was simplified into Moloch). It is possible that Moloch and Yahweh were once seen as one and the same.
In short, the Hebrew Testament (which has a different order than the Christian Old Testament) was written by those who wanted to remember ancient Israel as monotheistic when the reality was so different that bits of the truth leaked through the ink and stained the scrolls. This is but a very superficial examination of a complicated issue but the point is made: something is terribly amiss with this “only god” who demands that no other gods be put before him. Clearly, other gods were put before him quite often.
Here are some verses for further research:
Acts 7:41 And they made a calf in those days and offered sacrifice unto the idol, and rejoiced in the works of their own hands. 42 “Then God turned, and gave them up to the worship of the host of heaven, as it is written in the book of the Prophets: ‘O ye house of Israel, have ye offered to Me slain beasts and sacrifices for the space of forty years in the wilderness? 43 Yea, ye took up the tabernacle of Moloch and the star of your god Remphan, images which ye made to worship them. And I will carry you away beyond Babylon.’ [Remphan is Egyptian. Chiun is the Hebrew. Both mean the god Saturn.]
Amos 5:26 But ye have borne the tabernacle of your Moloch and Chiun your images, the star of your god which ye made for yourselves.
Leviticus 18:21 “‘Do not give any of your children to be sacrificed to Moloch, for you must not profane the name of your God. I am the Lord.
I Kings 11:7 On a hill east of Jerusalem, Solomon built a high place for Chemosh the detestable god of Moab, and for Moloch the detestable god of the Ammonites.
I Kings 11:33 I will do this because they have forsaken me and worshiped Ashtoreth the goddess of the Sidonians, Chemosh the god of the Moabites, and Moloch the god of the Ammonites, and have not walked in obedience to me, nor done what is right in my eyes, nor kept my decrees and laws as David, Solomon’s father, did.
II Kings 21:6 He sacrificed his own son in the fire, practiced divination, sought omens, and consulted mediums and spiritists. He did much evil in the eyes of the Lord, arousing his anger.
Jeremiah 32:35 They built high places for Baal in the Valley of Ben Hinnom to sacrifice their sons and daughters to Moloch, though I never commanded—nor did it enter my mind—that they should do such a detestable thing and so make Judah sin.
And the list goes on… I bid you happy research.
 Pagels, The Origin of Satan: How Christians Demonized Jews, Pagans, and Heretics, 44-47.
 Russell, Jeffrey Burton. The Devil, 99.
 Russell, 142.
 Russell, 170.