Divine supremacy in the Ancient Near East

Even many who have no preference for worship of YHWH alone over Canaanite polytheism tend to repeat the Hebrew Bibe's characterization of Canaanite gods as foreign to Judaean (and/or Israelite) religion. For example, the non-denominational History in the Bible podcast (episode 1.44 The House of Omri: Pinnacle of Power) calls the priests of the Ba‘alîm and of ’Ăšêrāh in the famous story of 1 Kings 18 "foreign":

1 Kings 18 ("Complete Jewish Bible" translation)
17 When Ach’av saw Eliyahu, Ach’av said to him, “Is it really you, you troubler of Isra’el?”
18 He answered, “I haven’t troubled Isra’el, you have, you and your father’s house, by abandoning Adonai's mitzvot [YHWH's commands] and following the ba‘alim [plural of Ba‘al].
19 Now order all Isra’el to assemble before me on Mount Karmel, along with the 450 prophets of Ba‘al and the 400 prophets of the asherah [hā-’ăšêrāh] who eat at Izevel’s table.”
20 Ach’av sent word to all the people of Isra’el and assembled the prophets together on Mount Karmel.
21 Eliyahu stepped forward before all the people and said, “How long are you going to jump back and forth between two positions? If Adonai [YHWH] is God [hā-’ĕlōhîm, "the god"], follow him; but if it’s Ba‘al, follow him!” The people answered him not a word.
22 Then Eliyahu said to the people, “I, I alone, am the only prophet of Adonai [YHWH] who is left, while Ba‘al’s prophets number 450.
23 Let them give us two young bulls, and they can choose the bull they want for themselves. Then let them cut it in pieces and lay it on the wood but put no fire under it. I will prepare the other bull, lay it on the wood and put no fire under it.
24 Then, you, call on the name of your god [’ĕlōhêkěm]; and I will call on the name of Adonai [YHWH]; and the God [hā-’ĕlōhîm, "the god"] who answers with fire, let him be God [hā-’ĕlōhîm, "the god"]!” All the people answered, “Good idea! Agreed!”

25-35 (The other priests do not succeed.)

36 Then, when it came time for offering the evening offering, Eliyahu the prophet approached and said, “Adonai, God [YHWH ’Ělōhîm, "god/God"] of Avraham, Yitz’chak and Isra’el, let it be known today that you are God [’Ělōhîm, "god/God"] in Isra’el, and that I am your servant, and that I have done all these things at your word.
37 Hear me, Adonai [YHWH], hear me, so that this people may know that you, Adonai [YHWH], are God [hā-’ĕlōhîm, "the god"], and that you are turning their hearts back to you.”
38 Then the fire of Adonai [YHWH] fell. It consumed the burnt offering, the wood, the stones and the dust; and it licked up the water in the trench.
39 When all the people saw it, they fell on their faces and said, “Adonai is God [YHWH, hūʾ hā-’ĕlōhîm, "YHWH, he (is) the god"]! Adonai is God!”
40 Eliyahu said to them, “Seize the prophets of Ba‘al! Don’t let one of them escape!” They seized them; and Eliyahu brought them down to Vadi Kishon and killed them there.

It's clear from the text, however, that there are not really multiple religions, focussed on different gods, with open-minded people tolerating each other's religions. Rather, Eliyahu (Elijah) is proposing something that his fellows are not ready to accept: that either the god he is priest of is "the god", or one of the deities they follow. Whether the story has any basis in historical events (I would guess probably not), the idea promoted by the text, which would come much later to be called monotheism, is historical, and it was an innovation at the time.

To promote this idea, the author plays with the multiple meanings of ’ĕlōhîm. Primarily, it means "god, deity", and this meaning is used to describe the three rivals all as "gods"; thus Ba‘al is hā-’ĕlōhîm, "the god", of his priests. But because ’Ělōhîm is also specifically a title or name of YHWH, the claim is made that if any other god is hā-’ĕlōhîm, "the god", then YHWH is not.

But as the text itself says, the priests have multiple ba‘alîm, "lords". They also have multiple ’ĕlōhîm, "gods", and these are not foreign. ’Ăšêrāh is the Hebrew form of a common West Semitic word (from a Common Semitic root), that is to say, it is inherited, not imported. She is not, pace Strong's Hebrew dictionary, a Phoenician goddess, but a goddess known to speakers of both Hebrew and Phoenician, two closely related Canaanite languages. Ba‘al, too, is an ordinary Hebrew word; ba‘al means "man, husband, lord", and when denoting a deity, it can be understood sometimes as a name, sometimes as a title, with no firm boundary: It is famously difficult for us today to tell whether Ba‘alîm are "forms" of Ba‘al (whatever that would mean) or share a common title, and what their relationship to the Ba‘al of mythology is; there are also plural ’ăšêrîm or ’ăšêrōṯ.

They are however easily confused with one deity that actually was foreign, and one that the anti-polytheistic authors liked to claim was foreign:

The former is Bēl (as he is known in both Greek and Hebrew, as well as the original Akkadian), originally an epithet of Marduk which later largely supplanted his name, from the Akkadian common noun bēlu, which is cognate with and has about the same meaning as the Hebrew common noun ba‘al. In the Hebrew of the Bibe, however, he is a distinctly Babylonian god, spelled differently from the Canaanite Ba‘al. They are also distinguished, for the most part, in Aramaic and Jewish/Christian Greek, with aram. byl and gr. Bēl[os] for the Babylonian, aram. b‘l and gr. Baal for the Canaanite god, although Greek pagan authors use Bēl for the Canaanite god as well. The reason for this may be that Canaanites had become speakers of Aramaic and called Ba‘al by the Aramaic equivalent B‘el, which could well have produced the Greek form Bēl. There is no direct evidence whatsoever of B‘el-Bēl syncretism in pagan Aramaic.

The latter is Astarte (the Greek form), Hebrew ‘Aštōreṯ, who is called ’ĕlōhê, "god", of the Sidonians (meaning Phoenicians) in 1 Kings 11:5. But like ’Ăšêrāh (who is etymologically unrelated), she is a goddess known to both Phoenicians and Hebrews because she had been worshipped by their common ancestors and continued to be worshipped by both peoples until well into the time when the ideology of monotheism had been formulated. The Hebrew Bibe mentions the worship of multiple ‘aštārōṯ (Judges 2:13, 10:6) among the Hebrews, pointing perhaps to a multitude of local cults.

Be that as it may, it is fairly well known by now that Judah and Israel were not people living side by side with the Canaanites, but developing, from Canaanite origins and surrounded by Canaanites, a new identity for themselves, a process known as ethnogenesis. At some point, this began to imply exclusive worship of the Judahite/Israelite god, YHWH, among Judahites/Israelites. This was possible because a self-assertive politics in the ancient Near East went with self-assertive theology: the god of the rulers could be claimed to be the most powerful, and the worship of that god could be imposed on the subjected populations (in addition to their own cults!), as was done by the Assyrians, who claimed the superiority of the god of their capital, Aššur, over all others, whom he had defeated.

Closer to home for the Judahites/Israelites, the power of a people's god was also tied to their political power; victories were won in the name and through the help of the "tribal" god. Judahites/Israelites thus had good reason to be suspicious of anyone among them worshipping the god of a different people, like Kmš, the god of the Moabites. (He is usually known as Chemosh, but that is probably a deliberately distorted vocalization).

This explains the persuasive power of a passage like this, again from the CJB:

Judges 10:6 Again the people of Isra’el did what was evil from Adonai’s perspective — they served the ba‘alim, the ‘ashtarot, the gods of Aram, the gods of Tzidon ["Sidon"], the gods of Mo’av ["Moab"], the gods of the people of ‘Amon and the gods of the P’lishtim. They abandoned Adonai and did not serve him;

Now it is typical of polytheistic cultures that while many gods are known and worshipped superregionally, they are associated particularly with a place where their worship is especially prominent. So, for example, Hera was also known as the Argive goddess, but her worship had not spread from Argos to the rest of Greece, but was already known to their common ancestors.

It was thus somewhat plausible to ancient Judahites/Israelites to claim that the worship of a goddess like Astarte, who was especially dear to the Phoenicians (like Hera to the Argives), had spread from them to the Hebrews. After all, people knew that some deities, even within Canaan (like Kmš), were not "common property", so to speak, but were associated with the welfare of other peoples, whose successes were their own defeats.

Unlike classical Greece, Canaan had developed a theology that proposed a council of gods headed by a god ʾĒl (as he is known in Hebrew), who had made each god the ruler over one country/people. The Hebrew faction for exclusive worship of YHWH considered ʾĒl to be another name of their own god, YHWH, and so psalm 82 has their god declare to the others (again from the CJB):

6 “My decree is: ‘You are elohim [gods, judges],
sons of the Most High all of you.
7 Nevertheless, you will die like mortals;
like any prince, you will fall.’”
8 Rise up, Elohim, and judge the earth;
for all the nations are yours.

It would probably be closer to the original intention to print ’ĕlōhîm both times, in the sense of "gods" (the gloss [gods, judges] is not by me in this case), and extend the direct speech to verse 8. Here we see the rise of YHWH to supremacy as the highest god, but the other gods are only demoted in power; they are still gods. This theology is different from that in 1 Kings, but it is probably its forerunner. Stressing the idea of the council of gods ruling over nations, rather than the idea of a council of gods who are each available to all people (as it is found, concurrently with the other model, in the literature of Canaanite Ugarit), enabled the so-called Yahwists to propagate exclusive worship of YHWH among Judahites/Israelites, and later Yahwists added to the ideology of exclusive worship a theology that YHWH was the only god, with the other "gods" either demons, or mere images, or nothing at all.