Little is known about the Israelite view of malevolent spirits, popularly called “demons” in contemporary usage. In contemporary usage. In addition to the Hebrew word shed, translate “false gods” in Ps 106:37, the OT has a Hebrew word sair, translated in the NIV as “goat idols” (Lev 17:7: 2 Chron 11:15: see the NIV text note on Lev 17:7). Some suggest that the use of sair also refers to demons in Isa 13:21; 34:14 (NIV “wild goats). This Hebrew word refers to an actual goat in Gen 37:31 and frequently in texts prescribing a goat for sacrifice (e.g., Lev 4:23; Nu 7:16).
The overlap in terms can be understood if the Israelites thought of malevolent spirits as normally inhabiting the hostile desert, where creatures such as wild goats were native. Some of the earliest Mesopotamian art might offer a parallel to Israelite conceptions of malevolent
spirits as goats. Among the Sumerians, one demon takes the form of an ibex-the wild goat well-known in Israel. Early Sumerian art (early third millennium BC) also depicts the composite figure of a bull-man, sometimes locked in combat with a human hero, representing an evil force of some kind. Closer to the Biblical imagery is a Late Babylonian (first millennium BC) commentary on an exorcism that describes two malevolent spirits as having the faces of goats. Egyptians also portrayed malevolent, lesser spirits in human and animal form.
This is all conjecture about how Israelites might have visualized such beings. Unfortunately, their function within the religion of Israel is equally unclear. Mesopotamians associated malevolent spirits with very specific illness and personal misfortune, and they named them accordingly. However, there are no indications in the OT as to how demons were thought to interface with the human realm. Israelites sacrificed to such beings, and perhaps physical images of them were involved (Lev 17:7 and NIV text note; 2 Chron 11:15; Psa 106:28). It is possible that Yahweh employed malevolent spirits to afflict judgment (1 Sam 16:14; 1 Kings 22:21-22); but here the general word for “spirit” is used, so the identity of the spirit within the ranks of the divine council is unknown. In later Judaism, a more elaborate theology of angels and demons developed, but the classifications assumed in contemporary Christianity were largely unknown in OT times