Next week is the holiday of Shavuot, which celebrates the national revelation of the Torah to the Jewish people 3,323 years ago. As such, it would seem an appropriate time to try and clarify some misconceptions regarding who exactly this Revealer is.
Over the years I have fielded a lot of questions along the lines of, "Rabbi, no one seriously believes in Thor or Isis anymore. Don't you think that the Jewish God will also eventually come to be considered equally as silly?" In such cases I try to explain that the nature of the question reveals that the questioner is making certain assumptions about the nature of God and is not fully familiar with the fundamentals of our understanding of what God is (and is not).
Contrary to popular conception, Judaism did not introduce monotheism to the world. Rather, it restored it. The Torah teaches that the earliest civilizations knew God's unified nature quite well but that there was an unfortunate descent of comprehension over the generations. In his epic work, "The Mishna Torah," Maimonides explained that these early people understood that there was one over-arching, transcendent entity who created and utilized "agents" to interface with the universe. They conceived of the sun as one such agent. Later they came to see it as proper to honor the servant as much as the master and in the course of time dispensed with the master in toto. This was rather self-serving in that now they could beseech the rain "god" in times of drought and the wheat "god" when their crops were in jeopardy. It was quid pro quo: worship in exchange for goods and services. The Jewish conception of God recoils at such reductive pigeonholing and identifies this opportunistic style of worship as the root of the idolatry that Abraham would eventually come to intellectually shatter.
The Torah does not deny the existence of other non-corporeal forces that serve, for example, as messengers between the physical and metaphysical worlds. These forces are referred to as "other gods." Time and again the people are advised to abjure these bit players (who are anyway inexorably under the sway of the Infinite God) and dedicate themselves to the more challenging task of connecting to the one true universal power. This force, when acting within the boundaries of time and space, is known as Elohim and Jewish law has recorded that the meaning of this name is "the master of all powers." There is another name known as YHVH that refers to God in His fully transcendent state. It is also interesting to note that in the Hebrew language the numerological value of the name Elohim equals the word for nature, implying that the natural world is but another expression of this unified power. Jewish practice, such as the daily recitation of the Shema prayer, is very focused on getting its adherents to realize that these two manifestations are one and the same.
Abraham was a spiritual giant. He observed the polytheistic world into which he was born and noted that the sun could not be all that powerful inasmuch as it disappeared for half the day -- and the same with the moon, the wind and all the forces of nature. Their limitation was their fatal defect. He deduced that all things that are limited have beginnings (and endings) and if they began, it was because something else caused them to begin. He surmised that there could not have been an infinite regress of these causes and the only way that our world of effects could have gotten rolling was through the activity of an original cause which itself was uncaused. In the English language this cause is called "God" and although the word can be borrowed and applied to the conception of a being that is very powerful yet limited, it fails to describe Elohim/YHVH, who is unbound by any imagined limitation whatsoever (time, space, matter, et al).
Both Abraham and Aristotle deduced through reason that this "Prime Mover" cannot have any properties of finite existence -- no body, no corporeal elements, no form, etc. He must be "one" in the organic sense that He can't be comprised of any parts. He must be inherently one and inherently indivisible. Maimonides (paraphrasing Aristotle) artfully proved these contentions in 26 steps at the beginning of the second section of his "Guide for the Perplexed." Therefore, Thor, Zeus, Isis and even the Flying Spaghetti Monster are all theoretically acceptable (if silly) appellations if they are being used to connote the Infinite and unbounded power that we are discussing. Otherwise, they are simply describing a conception of another created, finite entity like any other (and one that is not God.)
An infinite antecedent cause is logical and satisfactorily addresses the question of the origin of the universe. The concept has the added benefit of elegantly explaining conundrums such as, "OK, then where did God come from?" The answer, of course, is that He did not and indeed could not come from anywhere. If He did, He would be finite and not be God and we would be lost in the conundrum of the infinite regress. The Torah's contention is that nothing need create God as He is by definition beyond creation. That which is the cause of space, time and matter and exists outside of those properties obviously can not be bound by them.
There are those who suggest that a bubbling series of interlocked universes that ebb and flow into each other has always existed. They postulate that this is the true cause of our universe and therefore no conscious Creator is required to explain creation. Though, as Brian Greene wrote recently in "The Hidden Reality," "the subject of parallel universes is highly speculative. No experiement or observation has established that any version of the idea is realized in nature." So outside of seemingly being un-provable, this theory would appear to be yet another extension of the faulty notion that something that is either very powerful (Odin, Kronos, etc.) or unbelievably large (multiverse) is the same as infinite. Inasmuch as these theoretical universes exist as distinct and identifiable entities, it's reasonable to conclude that they (and by extension the whole multiverse) are in actuality finite -- and finite things do not create themselves.
So when people suggest that they "just believe in one god less than I do," I point out that from the Judaic vantage point there simply can be no other gods to believe in. Powerful transcendental (but finite) forces yes, but not God.