It is often said that monotheism is one of Judaism’s greatest contributions to Western culture; however, it is far from clear that the Hebrew Bible is monotheistic. What is monotheism and when did it first develop?

Numerical Monotheism and Philosophical Monotheism

No word in the Hebrew Bible can be rendered as monotheism. In fact, “monotheism,” derived from the Greek mono (one) + theism (belief in God), does not occur in English until the 17th century. The term itself can have more than one meaning.

From an etymological standpoint, simply believing in only one deity, even a corporeal divinity such as Zeus or Athena, qualifies one as a monotheist. We might call this numerical monotheism. In the philosophic tradition, however, monotheism involves more than an arithmetical claim: As the German Jewish philosopher, Hermann Cohen (1842–1918) said, the issue at stake is not so much oneness (einheit) as uniqueness (einzigheit).[1]

Although it would be impossible to discuss the development of monotheism without treating the Bible as a foundational text, even a cursory reading of the Bible leaves the reader wondering whether it advocates monotheism according to either definition, and if it does, how prevalent monotheism is. Nevertheless, I will argue below that the first definition of monotheism, and even intimations of the second, appear as early as Second Isaiah, although explicit articulation of the philosophic conception of monotheism did not emerge until well after the biblical period was closed.

The Evidence of the Torah

The Torah is never explicit about what central characters like Abraham and Moses thought about YHWH in the context of other gods. Although later Jewish tradition tells how Abraham disbelieved in other deities and even smashed his father’s idols, and thus became the first monotheist, this story is not in the Torah but in midrash (Gen. Rab. 33:18).[2] Certainly, the Torah depicts Abraham as a faithful servant of YHWH, but we are not told whether he thought YHWH was the only deity in existence or whether he thought YHWH reigned over a whole pantheon of deities.

This ambiguity carries over into the Book of Exodus, where at the Song of the Sea, which is the source of the Mi Chamocha prayer, the text asks:

שמות טו:יא מִי כָמֹכָה בָּאֵלִם יְ־הוָה

Exod 15:11 Who is like You, YHWH, among the gods?

The NJPS translation renders it “Who is like You, O LORD, among all the celestials?” Both versions raise an obvious question: Who or what are these gods or celestials? If they are actual entities albeit inferior to YHWH, then the passage would seem to mean that YHWH reigns over a pantheon of deities in much the same way that Zeus ruled over the gods of Mt. Olympus.[3]

An Anthropomorphic God

If it is unclear whether the Torah has a concept of numerical monotheism, it is even less clear that it has the philosophical concept of a non-corporeal God. Note the frequent use of anthropomorphic language to describe God: In the Bible, God carries on conversations with human beings, walks with Noah, eats with Abraham,[4] wrestles with Jacob, and descends on Mt. Sinai.[5] As Benjamin Sommer points out, the evidence that the God of the Hebrew Bible has a body is overwhelming.[6]

Other passages in the Bible exacerbate the problem. Exodus 24:10 says quite clearly that Moses, Aaron, and the elders of Israel saw God,

שמות כד:י וַיִּרְאוּ אֵת אֱלֹהֵי יִשְׂרָאֵל וְתַחַת רַגְלָיו כְּמַעֲשֵׂה לִבְנַת הַסַּפִּיר וּכְעֶצֶם הַשָּׁמַיִם לָטֹהַר.

Exod 24:10 and they saw the God of Israel: under His feet there was the likeness of a pavement of sapphire, like the very sky for purity.

This claim is echoed at Isaiah 6:1 and Ezekiel 1:26, where both prophets claim that they saw God in human form.

ישעיה ו:א …וָאֶרְאֶה אֶת אֲדֹנָי יֹשֵׁב עַל כִּסֵּא רָם וְנִשָּׂא וְשׁוּלָיו מְלֵאִים אֶת הַהֵיכָל.

Isa 6:1 …I beheld my Lord seated on a high and lofty throne; and the skirts of His robe filled the Temple.[7]

יחזקאל א:כו …וְעַל דְּמוּת הַכִּסֵּא דְּמוּת כְּמַרְאֵה אָדָם עָלָיו מִלְמָעְלָה.

Ezek 1:26 … and on top, upon this semblance of a throne, there was the semblance of a human form.[8]

If a person can see God, then it would be possible to sculpt a faithful image, assuming God would allow it. This brings up the question of how we are to understand the Decalogue’s command against crafting such images:

שמות כ:ד לֹא תַעֲשֶׂה לְךָ פֶסֶל וְכָל תְּמוּנָה אֲשֶׁר בַּשָּׁמַיִם מִמַּעַל וַאֲשֶׁר בָּאָרֶץ מִתַָּחַת וַאֲשֶׁר בַּמַּיִם מִתַּחַת לָאָרֶץ.

Exod 20:4 You shall not make for yourself a sculptured image, or any likeness of what is in the heavens above, or on the earth below, or in the waters under the earth.

We are never told why we are forbidden to do this. Is it that one could make a material image of YHWH but that is not how he wants to be worshipped? This would make the commandment a matter of divine preference. Or is it that YHWH is not corporeal so that any attempt to capture his likeness in stone or wood would be a distortion? This would make the commandment an expression of a metaphysical truth consistent with the philosophic conception of monotheism.

This kind of ambiguity clouds a number of passages that later scholars use to argue that the Bible has a conception of a non-corporeal God. For instance, Deuteronomy says that the people saw no form at Sinai:

דברים ד:יב וַיְדַבֵּר יְ־הוָה אֲלֵיכֶם מִתּוֹךְ הָאֵשׁ קוֹל דְּבָרִים אַתֶּם שֹׁמְעִים וּתְמוּנָה אֵינְכֶם רֹאִים זוּלָתִי קוֹל.

Deut 4:12 YHWH spoke to you out of the fire; you heard the sound of words but perceived no shape, nothing but a voice.

Nevertheless, it is unclear whether this means that God has a body but they didn’t see it, or that God has no body at all. A similar ambiguity arises from God’s comment to Moses on Mount Sinai:

שמות לג:כ וַיֹּאמֶר לֹא תוּכַל לִרְאֹת אֶת פָּנָי כִּי לֹא יִרְאַנִי הָאָדָם וָחָי.

Exod 33:20 He said, "You cannot see My face, for man may not see Me and live."

Does this mean that looking upon God’s face is dangerous, and someone who does so will die, and thus God is protecting Moses here, or does it mean that it is impossible to see God either visually or with one’s mind’s eye, since God is not a physical thing? As a modern academic Bible scholar, Benjamin Sommer understands the verse as God warning Moses of danger, while Maimonides, a philosopher who believed God is incorporeal, understood the verse as a philosophical statement about God’s incorporeality.[9]

Maimonides on God’s Unity

Even the famous words of the Shema are ambiguous:

דברים ו:ד שְׁמַע יִשְׂרָאֵל יְ־הוָה אֱלֹהֵינוּ יְ־הוָה אֶחָד

Deut 6:4 Hear, O Israel, YHWH (is) our God, YHWH (is) ʾeḥad.

What is this verse trying to communicate? Despite its brevity, many interpretations have been offered.

Monolatrous —Is it about loyalty, “YHWH alone is our God”? This would mean that there are other gods, but that they are not “ours.”

—Is it about loyalty, “YHWH alone is our God”? This would mean that there are other gods, but that they are not “ours.” Numerical Monotheism —Does it mean “YHWH is the only God,” which would be monotheistic according to the arithmetic understanding?

—Does it mean “YHWH is the only God,” which would be monotheistic according to the arithmetic understanding? Philosophical Monotheism—­Does it mean “YHWH is one,” i.e., that in addition to being the only God, YHWH is unified and unlike anything else?[10]

Not surprisingly, Maimonides opted for the philosophical interpretation.[11] According to him, אֶחָד (one) should be taken to mean that God cannot admit diversity in any form so that it is wrong to think that God has multiple faculties, attributes, emotions, or mental states.

Confronted with dozens of passages that seem to ascribe material predicates to God—e.g., God sees, sits, speaks, descends—Maimonides argued that they must be reinterpreted in a way that excludes materiality. For example, “God sees” should be understood as “God knows.”[12] “God speaks” should be understood as “The prophet understands what God wants.”[13] “God descends” should be understood as “God’s revelation to the prophet is about to begin.”[14] (Maimonides actually takes this even further, see appendix.)

Most Bible scholars would agree that this is not the original meaning of these texts, or of the Shema. Furthermore, even Maimonides would admit that this is not even the “current” meaning of the texts; in other words, this is not what millions of people mean when they recite the Shema or read the Bible. But Maimonides’ basic assumption is that most people do not really understand the “real” meaning of such verses, and that only people who have studied philosophy and reflected on these concepts for years will see the point a biblical verse is trying to make.

The Sin of Idolatry: From the Torah to Second Isaiah

Having noted the ambiguity in the Bible about monotheism, whether numerical or philosophical, the question becomes: Can we find a clear statement about monotheism of any kind anywhere in the Bible? Our first impulse might be to turn to the prohibition against worshipping other gods in the Decalogue:

שמות כ:ג לֹא יִהְיֶה לְךָ אֱלֹהִים אֲחֵרִים עַל פָּנָיַ.

Exod 20:3 You shall have no other gods besides Me.

This statement too, however, is ambiguous. Is worship of other gods prohibited because the other gods are unreal or because YHWH is an impassioned, jealous God who demands complete loyalty from his worshippers (Exod 34:14)? To put it another way, is worship of other deities a moral failing (“You promised to worship YHWH alone and now you have broken your word by worshipping other deities”) or an intellectual one (“You are worshipping an illusion, something that does not exist”)?[15]

The end of the Torah (Deut 31:16) contains a strongly worded statement of the first view, comparing idolatry to adultery:

דברים לא:טז … וְקָם הָעָם הַזֶּה וְזָנָה אַחֲרֵי אֱלֹהֵי נֵכַר הָאָרֶץ אֲשֶׁר הוּא בָא שָׁמָּה בְּקִרְבּוֹ וַעֲזָבַנִי וְהֵפֵר אֶת בְּרִיתִי אֲשֶׁר כָּרַתִּי אִתּוֹ.

Deut 31:16 …This people will thereupon go astray after the alien gods in their midst, in the land that they are about to enter; they will forsake Me and break My covenant that I made with them.

We do eventually encounter the second view, according to which only a fool would bow down to something she made with her own hands, in the work of Second Isaiah, an exilic period prophet whose writings occupy chapters 40-55 of the Book of Isaiah.[16]

Monotheism in Second Isaiah

Little is known about Second Isaiah’s life, not even his name, except that he lived after Jerusalem fell to the Babylonians in 586 B.C.E. Second Isaiah’s phrasing of a monotheistic creed is as a statement from God:

ישעיה מד:ו אֲנִי רִאשׁוֹן וַאֲנִי אַחֲרוֹן

וּמִבַּלְעָדַי אֵין אֱלֹהִים.

Isa 44:6 I am the first and I am the last;

And there is no god but Me.[17]

This claim rules out any suggestion that God’s sovereignty derives from the fact that he rules over a plethora of other gods.[18] So it is not that the gods recognized by polytheistic religions are less powerful than YHWH but that they simply do not exit. Accordingly,

ישעיה מא:כא הֵן כֻּלָּם אָוֶן

אֶפֶס מַעֲשֵׂיהֶם

רוּחַ וָתֹהוּ נִסְכֵּיהֶם.

Isa 41:29 See, they are all nothingness,

Their works are nullity,

Their statues are naught and nil.

If this is true, then anyone who prays or bows down to idols is a fool. Thus, for Second Isaiah, idolatry is an intellectual failing. As he says several times, the statues that people erect to their gods are made by human hands; they cannot say anything, do anything, or think anything. Anyone who worships or seeks comfort from them is deluded and,

ישעיה מד:כ וְלֹא יֹאמַרהֲלוֹא שֶׁקֶר בִּימִינִי

.Isa 44:20 Never says to himself, “The thing in my hand is a fraud!”

What about philosophical monotheism, that God is essentially incomparable to anything else? I would argue that the seeds of this idea can be found in Second Isaiah as well, in his discussion of the prohibition against making forms.

God Is Incomparable

Recall the wording of the second commandment: “You shall not make for yourself a sculptured image, or any likeness of what is in the heavens above, or on the earth below, or in the waters under the earth.” In other words, there is no such thing as a good versus a bad likeness because they are all doomed from the start. How is this prohibition understood monotheistically?

Suppose we take a purely numerical approach, and assume that YHWH is corporeal but does not want his image to be cast in stone or wood. Note that on this interpretation, nothing would prevent one from forming an image of YHWH in one’s mind. Suppose too that one conceives of corporeality as implying a human form. Is that form male or female? Thin or stout? Dark or fair? Curly hair or straight? These are all options; a corporeal YHWH must look like something after all, we just don’t happen to know what.

The crux of the philosophic conception of monotheism is that these questions are ridiculous; as God is incorporeal, all images are distortions, whether the image is mental or physical. The problem of making an image is because YHWH has no image at all.Second Isaiah expresses this latter point when he asks:

ישעיה מ:יח וְאֶל מִי תְּדַמְּיוּן אֵלוּמַה דְּמוּת תַּעַרְכוּ לוֹ.

Isa 40:18 To whom, then, can you liken God, What form compare to Him?

In other words, Second Isaiah’s understanding of the prohibition is in line with the philosophical concept and not merely the numerical one. As he tells us in the same chapter, the mightiest nations on earth are as nothing before God – indeed, less than nothing. I take this to mean that the mightiest rulers, warriors, or castles are as nothing as well.[19]

By implication, the same is true of tidal waves, thunderbolts, sea monsters, or heavenly bodies. Although mighty in their own way, these things are part of the created order and therefore owe their existence to the Creator. God is not like these created materials but is utterly unique, in a class entirely by Godself.

Second Isaiah and the Seeds of Philosophical Monotheism

Although Second Isaiah does not phrase the point like a medieval philosopher—nor did he likely realize the full implications of what he said—the seeds of the point that Maimonides developed more than a millennium later are already there.[20] The shift from the vaguer notions in the Shema or Song of the Sea about loyalty to YHWH to the monotheistic notions of Second Isaiah that YHWH is the only God, culminate in the philosophical monotheism of the Middle Ages.

This shows us that monotheism did not emerge all at once, like a lightbulb turning on in an ancient prophet’s mind, but the concept developed in distinct, but conceptually linked stages.[21] While the Torah emphasized the importance of loyalty to YHWH, and introduced a prohibition to present YHWH in physical form, Second Isaiah concretized the first point as monotheism and understood the second as deriving from YHWH’s existence as a unique being. This, in turn, laid the groundwork for the philosophical tradition about the incorporeal God.

Thus, monotheism should not be seen as simply an idea or proposition that was set forth at some point in the distant past. Instead, the Israelite speculations about the place of their God in the universe set in motion a vibrant set of interrelated concepts about God that has held up for over two millennia and stimulated the minds of millions of worshippers.

Addendum

God’s Unity and the Problem of Anthropopathism

Maimonides takes the concept of God’s unity very far, arguing that if God cannot admit diversity, then God cannot undergo any kind of change. This is because saying that God went from one state, e.g., being angry, to another, being pleased, would be to ascribe multiple states to God.[22]

This leads to the question of how far to take the rejection of anthropomorphism. According to one line of thought, any ascription of personality to God, e.g. the ability to plan, love, experience emotion, approve of some things and disapprove of others compromises God’s uniqueness. According to another line of thought, some form of personality is essential to our idea of divinity.

Whatever its philosophic merit, the first alternative is hard to accept because God becomes so mysterious as to seem unapproachable. Moreover, a God devoid of any feelings would be so far removed from the God described in the Bible that reading the Bible would be of little help in trying to understand such a God. To this day, scholars debate how far Maimonides himself went in formulating his conception of God. Although his masterpiece is entitled The Guide of the Perplexed, he admits that he cannot resolve every question that may come up.