Philosopher Moses Maimonides believed that superstition undermines Judaism as a rational belief system. For him, the purpose of mezuzah has nothing to do with protection, but rather, serves as a didactic device that teaches us about the importance of making ethical monotheism a part of our daily lives. There can be no doubt that Maimonides would have considered the Lubavitcher Rebbe’s mitzvah campaign of promoting the mezuzah as well-meaning, but theologically foolish–and perhaps even pagan-esque, since it devalues the purpose of God’s commandments.
The Psychology of Amulets
Maimonides contrasts religion and superstition in his discussion about using incantations to heal a wound:
“Anyone who whispers a incantation over a wound and reads a verse from the Torah, or one who recites a biblical verse over a child so he won’t be frightened, or one who places a Torah scroll or tefillin over an infant to enable him to sleep, are not only included in the category of sorcerers and charmers, but are included among those who repudiate the Torah. They use the words of the Torah as a physical cure, whereas they are exclusively a cure for the soul, as it is written, ‘they will be life to your soul.’ On the other hand, one who is enjoying good health is permitted to recite biblical verses, or a psalm, that he may be shielded and saved from affliction and damage by virtue of the reading.” 
He further states: The ancient Sages said, “Whoever has tefillin on his head and arm, tsitsit on his garment, and a mezuzah on his door can rest assure that he will not sin,” for he has many reminders, and these are the “angels” who will save him from sinning, as it is said, “The angel of the LORD, who encamps with them, delivers all who fear God” [Ps. 34:8].” For Maimonides, the rituals of Judaism serve one purpose only: to teach the worshiper how to become mindful of God’s commandments. 
For Maimonides, the power of the mezuzah, tefillin (phylacteries), or other ritual items rests in their ability to convey the meaning of faith to its faith community. They are not magical amulets, nor do they have holiness in and by themselves. Maimonides took a dim view of men who, in his generation, claimed to use God’s Names for theurgical (magical) purposes. In referring to the writers and hucksters of magical healing amulets, he writes: “Do not let occur to your mind the vain imaginings of the writers of amulets or names you may hear from them or what you may find in their stupid books, names they have invented and… they think work miracles. All these are stories that it is not seemly for a perfect man to listen to, much less to believe.” 
Much in the same spirit as Maimonides, Josephus, (c. 37-100 C.E.) also attests to antiquity of the mezuzah, and speaks of it as well-established custom. Inscribed with passages of the Torah which emphasize the unity of God, His providence, and the resulting duty of man toward Him, the mezuzah is an emblematic representation of Israel’s belief and practice. Thus Josephus says in speaking of the mezuzah (l.c.): “The greatest benefits of God are to be written on the doors . . . in order that His benevolent providence may be made known everywhere” .
The Nature of a Fetish
There is an interesting anthropological term that may shed some light on our discussion–the fetish. According to the ethnology of the 19th and early 20th centuries, the term “fetishism” was used to describe the veneration of certain objects (rocks, trees, teeth, and so on ) that were thought to possess spirits or to have special powers. Such veneration is said to be one of the defining qualities of the so-called tribal societies.
Other thinkers argue that the “fetish,” refers to “irrational” modes of conduct in our own society. Thus, for example, I. Kant (1724–1804) said that a fetish is any form of worship that consists essentially not of moral principles but of mere rules of faith. We might add that any faith can become a fetish when its participants merely follow the rituals without ever contemplating the deeper meaning of what they are doing.
Even the Tablets Can Become a Fetish
Like Maimonides before him, Rabbi Meir Simcha of Dvinsk (ca. early 20th century) recognized the dangers in transforming Jewish ritual objects into a fetish. The writer raises an important question: How could Moses destroy the Ten Commandments? Surely if one destroyed a Torah scroll, such an act would be considered sacrilege; how much more so with the Tablets, since the Tablets were written by God Himself!? Rabbi Meir Simcha explains in his Torah Commentary:
“Torah and faith are the main aspects of the Jewish faith and all its sanctities, e.g., Eretz Yisrael (“the Land of Israel”), Jerusalem—are only a means to an end, not ends in and of themselves. Do not think that the sanctuary and the Temple are holy objects in their own right. Far be it! God dwells among His people and if they were like Adam who violated the covenant, all their sanctity is removed and they become as profane objects. . . . Moreover, even the Tablets which were written by God Himself, are not holy per se, but are so only because of you–if you observe them. When the Israelites acted disgracefully under the bridal canopy by consorting with the Golden Calf, the Tablets became as mere pottery. By themselves, they have no sanctity. The Tablets become holy only if it inspires a religious life suffused with ethical behavior. There is nothing in this world that is holy except for God. Nothing in Creation is holy in itself; through Torah, Creation becomes sanctified and made holy. I wish these words would be written on the walls of every synagogue!” 
Judaism as an Evolving Religion
The genius of Judaic tradition lied in its ability to transform an already existing superstition, and they converted it into vehicle of faith in conveying a message of ethical monotheism. Any attempt to re-transform these ritual items represents a retrogression to a more primitive stage of our faith’s evolution and development.
If Maimonides were alive today, he would be astounded to see rabbinic scholars revert to a more atavistic form of Judaism that he tried so hard to eliminate for a more enlightened future. It is safe to say that Maimonides would have concurred with the late physicist Carl Sagan, who wisely observed:
“I worry that, especially as the Millennium edges near, pseudoscience and superstition will seem year by year more tempting, the siren song of unreason more sonorous and attractive. Where have we heard it before? Whenever our ethnic or national prejudices are aroused, in times of scarcity, during challenges to national self-esteem or nerve, when we agonize about our diminished cosmic place and purpose, or when fanaticism is bubbling up around us – then, habits of thought familiar from ages past reach for the controls. The candle flame gutters. Its little pool of light trembles. Darkness gathers. The demons begin to stir.” 
 MT Hilchot Avoda Zara 11:12. Cf. Maimonides was opposed to the use of amulets. Cf. MT Hilchot Tefillin 5:4; Guide 1:61.
 Maimonides, MT Hilchot Tefillin u-Mezuzah 6:13.
 In his Guide, Maimonides comments how charlatans dupe the public by using God’s holy Name to “perform miracles,” and noted, “When bad and foolish men were reading such passages, they considered them to be a support of their false pretensions and of their assertion that they could, by means of an arbitrary combination of letters, form a shem (“a name”) which would act and operate miraculously when written or spoken in a certain particular way. Such fictions, originally invented by foolish men, were in the course of time committed to writing, and came into the hands of good but weak-minded and ignorant persons who were unable to discriminate between truth and falsehood, and made a secret of these shemot (names). When after the death of such persons those writings were discovered among their papers, it was believed that they contained truths; for, The simpleton believes everything” (Prov. 14:15).
 Antiquities iv. 8, § 13.
 Meshech Chochma, Parshat Ki Tissa.
 Carl Sagan, “The Demon-Haunted World: Science as a Candle in the Dark” (Ballentine Books, 1997), 25.