Satan in the Old Testament
Although English Bibles continue to capitalize the word satan in passages like Job 1 and 2, those passage do not have a specific individual in mind. That is, satan in these passages should not be understood as a proper personal name.
The reason this is the case is a rule of Hebrew grammar. In biblical Hebrew, the definite article (the word “the”) is a single letter (הַ; ha). Hebrew prefixes (attaches) the definite article to a noun (or participle to make it a substantive) so that, like all languages that have definite articles, the noun is made specific. However, biblical Hebrew does not put the definite article (“the”) on proper personal nouns (personal names). An example of this can be seen in English. I don't call myself “the Mike,” and Hebrew simply does not do this either (at all). In their biblical Hebrew reference grammar, Jouon-Muraoka note, “No proper noun of person takes the article, not even when it has the form of an adjective or a participle” (Paul Jouon and Takamitsu Muraoka, A Grammar of Biblical Hebrew (Editrice Pontificio Istituto Biblico, 2003; 2005), vol. 2:505; Par 137.b).
Satan in the Old Testament: The Book of Job
Without exception, the word satan in Job occurs with the Hebrew definite article. Here is a Hebrew search showing this to be the case. This indicates quite clearly that satan is not a personal name. It is generic and means “the adversary.” The word can also be used of human beings (1 Sam 29:4; 2 Sam 19:23; 1 Kings 5:18; 1 Kings 11:14). All of these examples have satan without the article, but the referent is a human being, not a divine being, so satan isn’t here either.
Satan in the Old Testament: Men and Angels
One might ask at this point whether there are instances where satanoccurs in the Hebrew Bible without the definite article. If there are such instances, might those occurrences of the term point to the Devil?
In terms of statistics, the noun satan occurs 27 times in the Hebrew Bible. Ten of those occurrences are without the article. Of these ten occurrences, seven refer to human beings and two refer to the Angel of Yahweh. That means nine of the ten instances clearly do not refer to the Devil or proper personal name, Satan.
The lone remainder is 1 Chronicles 21:1. This is the famous passage where satan provokes David to take a census, but in the parallel passage, 2 Samuel 24:1–25, Yahweh provokes David to take the census. Due to this parallel, and due to the fact that satan here has no article, this is viewed by some as the single instance of an evil, cosmic figure called satan in the OT. That’s actually not the case, though.
If one reads the Chronicles account of the census judgment carefully (the one that said satanprovoked the act), the destroying Angel is there “with a sword drawn in his hand.” The Hebrew phrasing behind this occurs only three other times: Joshua 5:13 and Numbers 22:23, 31. All three of these references are the Angel of Yahweh, and in one of them (Num. 22:23) he is referred to as “the satan.”
This connection back to the Angel of Yahweh is important. If you're familiar with my work on the two Yahwehs in the Old Testament, the likely explanation of the presumed contradiction between the two accounts of David’s census is that bothaccounts have the God of Israel instigating the census in order to judge David. This is because the Angel of Yahweh is at times equated with Yahweh. One could read the Chronicles account in light of that association. The Angel of the Yahweh was the satanfigure—both in judgment and in terms of instigation. There is no contradiction.
Lastly, this would in turn mean there are no verses in the Old Testament that have a personal name satan.
Satan in the Old Testament: What about the Serpent?
The satan in Job is an officer of the divine council (similar to a prosecutor). His job is to “run to and fro throughout the earth” to see who is and who is not obeying Yahweh. When he finds someone who is under Yahweh's wrath, he “accuses” that person. This is what we see in Job (and in Zechariah 3), and it actually has a distinct New Testament flavor. But the point here is that this satan in Job 1-2 is not evil. In fact, he's doing his job.
Over time, the idea of “being an adversary in the heavenly council” was applied intellectually to the enemy of God—the nachash (typically rendered “serpent”) in Eden, the one who asserted his own will against Yahweh's designs. This makes sense because the Fall resulted in humanity being estranged from God because of sin. This situation was caused by the serpent, who becomes the archetypal enemy of God in the biblical story. The serpent therefore understandably became labeled with the term satanbecause of this adversarial act and its (pardon the pun) fallout. The connection became so familiar that, eventually, satanbecame a proper personal noun after the Old Testament period during what’s called the Second Temple (“Intertestamental”) Period. This is why the name Satan appears in the New Testament and applied to the enemy of Eden.
This is a good example of how an idea in Israelite religion plays out and is applied in different ways during the progress of revelation. God certainly does have a great enemy in the biblical story, one that surfaces in Eden. The point here is that his enemy never gets called “Satan” until the periods after the Old Testament.