In ancient Jewish texts, there was a process of internalising forms of supernatural evil, wherein one’s sinful inclinations come from within each person themselves, and not from an external, supernatural evil (Satan and demons). The literature and scholarship on the yetzer hara has been summarised rather handily in a volume by Ishay Rosen-Zvi, Demonic Desires: Yetzer Hara and the Problem of Evil in Late Antiquity (University of Pennsylvania Press, 2011).
This understanding is found in texts such as 4QBarki Napshic (4Q436) from Qumran, wherein the “evil inclination” (the yetzer hara), is an internal evil tendency rather than an external supernatural being; the text reads, in part, “Yetzer ra you have rebuked from my kidneys, a holy spirit you have placed in my heart” (Demonic Desires, p. 47).
We see this throughout a lot of the literature, including Sirach 21:27. The NRSV renders the verse as follows:
When an ungodly person curses an adversary, he curses himself.
The LXX of this verse reads:
ἐν τῷ καταρᾶσθαι ἀσεβῆ τὸν σατανᾶν αὐτὸς καταρᾶται τὴν ἑαυτοῦ ψυχήν
Here, σατανας is coupled with the person's own bad impulses (the yetzer hara). That the term “Satan” can be used to denote an adversary, not just “Satan” in the traditional sense can be seen throughout the Hebrew Bible:
And God's anger was kindled because he went: and the angel of the Lord stood in the way for an adversary against him. Now he was riding upon his ass, and his two servants were with him. (Num 22:22; cf. v. 32)
Here, the angel of the Lord is said to be, according to the Hebrew, a "satan" or "adversary" (שָׂטָן).
There are a few places in the Book of Mormon where the locution, "the evil one" is paralleled with the person, not an external, supernatural Satan which seems to be consistent with this ancient Jewish concept. Consider the following few examples:
And why should I yield to sin, because of my flesh? Yea, why should I give way to temptations, that the evil one have place in my heart to destroy my peace and afflict my soul? Why am I angry because of mine enemy? (2 Nephi 4:27)
O that cunning plan of the evil one! O the vainness, and the frailties, and the foolishness of men! When they are learned they think they are wise, and they hearken not unto the counsel of god, for they set it aside, supposing they know of themselves, wherefore, their wisdom is foolishness and it profieth them not. And they shall perish. (2 Nephi 9:28)
It appears that one can make a somewhat plausible exegetical case that the yetzer hara appears in the Book of Mormon.
