The essence of Judaism is the belief in the One G‑d. Indeed, all monotheistic faiths trace their origin to Abraham, the discoverer (or re-discoverer) of this truth.
The Jewish belief in G‑d is expressed in the first two of the Ten Commandments. The first affirms the truth of His being. The second is the negative complement to the first--the disavowal of idolatry. Idolatry is not necessarily a lack of belief in G‑d; indeed, the Second Commandment begins, "You shall have no other gods before Me..." Rather, idolatry also includes any denial of G‑d's oneness -- his absolute singularity, unity and exclusiveness of being. To ascribe any divisions or compartmentalizations to the divine being, or to believe that G‑d has any partners or intermediaries to His creation and sustenance of the universe, is to transgress the prohibition of idolatry.
The particulars of the laws of idolatry are spelled out by Maimonides in his Mishneh Torah, in a twelve-chapter section entitled Laws Concerning Idolatry and its Customs. Here Maimonides defines idolatry and examines the various forms of idol-worship and its accompanying practices, the penalties they carry, the status of an idolator, etc.
In the first chapter of Laws Concerning Idolatry, Maimonides outlines the history of man's recognition of the truth of the One G‑d. Originally, man knew his Maker; but "in the generation of Enosh (Adam's grandson), humanity erred grievously, and the wisdom of that generations wise men was confused; Enosh himself was among those who erred. Their error lay in that they believed that it would be pleasing to G‑d if they were to venerate the forces of nature which serve Him, as a king desires that his ministers and servants be venerated. Soon they were erecting temples and altars to the sun and the stars, offering sacrifices and hymns of praise to them, believing all this to be the will of G‑d."
In later generations, Maimonides continues, "there arose false prophets... and other charlatans who claimed to have received communications from the various heavenly bodies as to how they are to be served and which images are to represent them. As the years went by, the venerable and awesome name of G‑d was forgotten from the lips and minds of humanity; no longer were they aware of Him at all. The common folk knew only the wood or stone image in its stone temple which they had been trained from childhood to bow down to and serve and swear by; the wiser ones among them believed in the stars and constellations that these images represented; but none recognized or even knew of the Creator except for rare individuals such as Enoch, Methuselah, Noah, Shem and Eber. And so the world turned until the pillar of the universe, our father Abraham, was born.
"No sooner was [Abraham] weaned -- and he was but a small child -- that his mind began to seek and wonder: How do the heavenly bodies orbit without a moving force? Who moves them? They cannot move themselves! Immersed amongst the foolish idol-worshippers of Ur Casdim, he had no one to teach him anything; his father, mother and countrymen, and he amongst them, all worshipped idols. But his heart sought, and came to know that there is one G‑d... who created all and that in all existence there is none other than Him. He came to know that the entire world erred...
"At the age of forty, Abraham recognized his Creator... He began to debate with the people of Ur Casdim... He smashed the idols, and began to teach the people that it is only fitting to serve the one G‑d... He continued to call in a great voice to the world, teaching them that there is one G‑d for the entire universe, and that He alone is it fitting to serve. He carried his call from city to city and from kingdom to kingdom... Many gathered to ask about his words, and he would explain to each according to his understanding until he had shown him the path of truth. Thousands and then tens of thousands joined him...and he implanted this great principle in their heart and wrote many books on it. After Abraham's passing, Isaac, and then Jacob, continued his work, until Jacob's descendents, and those who joined them, formed a nation that knew G‑d.
"However, when the people of Israel dwelled in Egypt for many years, they regressed to learn from the behavior of the Egyptians and to worship idols with them... just a little longer, and the great principle implanted by Abraham would have been uprooted, and the descendents of Jacob would have reverted to the error of humanity and their contorted ways. But out of G‑d's love to us, and His keeping of the oath He made to Abraham... G‑d chose Israel as His, crowned them with mitzvot, and instructed them the way in which to serve Him, and the laws concerning idolatry and those who err with it."
Thus Maimonides concludes the first chapter of Laws Concerning Idolatry. In the next eleven chapters he proceeds to spell out the legal particulars of "idolatry and those who err with it."
The Mishneh Torah is a purely Halachic, or legal, work. On the rare occasions on which Maimonides digresses with an historical fact or a philosophical insight, it is always revealed, upon closer examination, to be a legally instructive point. The same is true of the opening chapter of Laws Concerning Idolatry: every detail of this lengthy history is a Halachah, a crucial component of the Torah's prohibition of idolatry. In this essay, we will dwell on two of the important points that Maimonides is making in this chapter.
Maimonides' first point is that idolatry is not only a religious sin but also a rational error. Enosh's generation "erred grievously and the wisdom of that generation's wise men was confused"; humanity was deceived by false prophets and charlatans. Abraham arrived at the truth of G‑d's oneness not by Divine revelation or supernatural powers, but in a process by which "his mind began to seek and wander... until he comprehended the truth and understood the righteous path by his sound wisdom." He gained adherents to his faith not by working wonders or prophesying in the name of G‑d, but by explaining to each according to his understanding, until he had shown him the path of truth. Maimonides does not mention G‑d's many revelations to Abraham (see Genesis 12:1, 12:7 15:1-21, et al); he also makes no mention of the many prophecies and miracles that accompanied the development of the nation that knew G‑d in its formative years. For even if none of this had come to pass, man could still have come to recognize the oneness of G‑d, and would have been expected to do so. Idolatry is irrational; man, using nothing more than his capacity to reason, can discern its fallacy and discover the truth.
[This is also emphasized by Maimonides' statement that "At the age of forty, Abraham recognized his Creator." There exist several accounts as to the year of Abraham's discovery. The Talmud states that Abraham recognized his Creator at age three; other sources cite his age at the time as 4; other as 50. Maimonides' source seems to be a variant version of the Midrash that states that he was 48t. As many commentaries suggest, there is no contradiction between these accounts -- each represents another level of recognition achieved by Abraham; indeed, Maimonides himself informs us that his quest began "soon after he was weaned, and he was but a small child." Why, then, does Maimonides choose to speak particularly of the recognition Abraham attained at age forty? Indeed, of what Halachic significance is Abraham's age at all? But Maimonides wishes to again underscore that Abraham's refutation of idolatry was a rational one. Forty is described by our sages as "the age of understanding" -- the point at which a person's cognitive powers attain full maturity. Thus, the level of discovery Abraham achieved at age forty represents his ultimate understanding of the divine truth.]
On the other hand, near the end of the historical account, Maimonides makes the very opposite point: without Divine intervention, the faith founded by Abraham would not have survived.
Human reason is not enough. It can expose fallacies, discover truth, transform a life, convince thousands, found a nation. But it is only as strong as the human self of which it springs. It can be distorted and suppressed by the tribulations of life: break the person, and you have invalidated his or her ideas. The exile and hardship experienced by the Israelites in Egypt almost destroyed the nation that knew G‑d. If G‑d had not revealed Himself to us at Sinai, the great principle implanted by Abraham would have been uprooted.
In the first chapter of Laws Concerning Idolatry, Maimonides is instructing us how the mitzvah "You shall have no other gods before Me" is to be observed.
It is not enough to say: "G‑d revealed Himself to us at Sinai and told us that there are no other deities or forces that are partner to His being and His rulership of the universe. So I know that it is so. If He said so, that's enough for me: the logic of this truth is irrelevant." No, says Maimonides. The Second Commandment obligates the Jew that his mind, not only his convictions, should negate the possibility of other gods. He must not only accept that this is so, but also comprehend that, rationally, it cannot be otherwise. Every Jew is commanded to develop the recognition of Divine truth attained by Abraham: a recognition so absolute that it can, by the force of reason alone, dispel a universally entrenched doctrine and convince thousands to transform their lives.
On the other hand, a person might take this to the other extreme, and say: "The oneness of G‑d is not a matter of faith, it's a fact. The nature of reality attests to it--I can prove it to anyone. It is the revelation at Sinai that is irrelevant. Monotheism is a rational truth, supported by irrefutable arguments."
That may be so, Maimonides is saying, but the Jew's denial of alien gods is more than an irrefutable philosophy. It is a faith implanted in the core of our souls, which endures also when logic ceases to function and reason is rendered impotent. To truly believe one must comprehend, but comprehension alone is but the mortal shadow of immortal faith. The philosophy-faith of Abraham barely survived Egypt; the supra-rational faith we attained at Sinai, where G‑d chose Israel as His, crowned them with mitzvot, and instructed them the way in which to serve Him, has survived a hundred Egypts and every madness of history.