We take it for granted that there will be a mezuza on the doorpost of a Jewish home. But like most things we take for granted, we frequently stop thinking about what that signifies. Unfortunately, for many people the mezuza has a superstitious connotation. It has become a good luck charm that is supposed to protect the home against harm and misfortune. Indeed there are zealous groups that make it their business to go around inspecting mezuzot and warning people of the disaster that awaits them if the mezuza is not kosher. Unfortunately the mezuza lends itself all too easily to this misinterpretation, mainly because of the association with the story of the blood on the doorposts when the 10th plague struck in Egypt (Exodus 12:22-23). The Torah itself makes no such connection. The blood on the doorposts in Egypt is not to be repeated and is never mentioned in the Torah in connection with the mezuza. Such superstition, however, has a long history. Maimonides in his time warned against it, saying that such a use turned the mezuza from a way of unifying God's name into a mere charm for personal benefit. The mezuza, he taught, like tefillin and tzitzit, is a reminder, keeping one from transgressing. (Hilchot Tefillin U'mezuza 5:4; 6:13). The command to have a mezuza is found twice in the Torah. It is in the first two sections of the Shema - Deuteronomy 6:4-9 and 11:13-21. These sections are contained in the mezuza. And a careful reading of these texts makes it very clear that the mezuza has no protective purpose. It is intended, rather, as a reminder of the importance of studying, teaching and relaying the basic beliefs of Judaism. The key word is "words" - "these words which I command you shall be upon your heart" (6:6). You shall teach them, recite them at all times, bind them upon yourself as a symbol and inscribe them on your doorposts and gates (6:7-9). The purpose of the mezuza is clear. By writing "these words" on the entrance to our homes we are both affirming our belief in what these words say and reminding ourselves of them and of our responsibility to repeat them and pass them on. It is also most probable that originally they were written on the doorposts in such a way that one would actually see them when going in and out. The current custom, which developed later, was to enclose them in a capsule (Sifre Deuteronomy 36). What exactly are "these words" that are so important that they are to be written and rehearsed? Although in a general sense it might seem to apply to all the words of Torah, this cannot be the intent concerning writing them on the doorposts. There simply is not room. The sages imply that it means these specific portions of the Torah that are encased in the mezuza (Sifre Deuteronomy 34). Another possibility is that it means to write the words that precede the instruction of teaching and writing them. That would mean: Hear O Israel, the Lord is our God, the Lord is one. And you shall love the Lord your God with all your heart and with all your soul and with all your might (Deuteronomy 6:4-5). Similar words are found in the second section commanding the mezuza - "...loving the Lord your God and serving Him with all your heart and soul" (Deuteronomy 11:13). These words - affirming our belief in the one and only God, the Lord (the four letter name of God made known to Moses at the burning bush), and requiring us to love the Lord and serve the Lord with all we are and all we have - encapsulate the very essence of Jewish belief. Essentially then, the mezuza, like the tzitzit, is a reminder to us. The tzitzit are a reminder to observe all of the mitzvot, as it says, "Look at it and recall all the commandments of the Lord and observe them" (Numbers 15:39). The mezuza, on the other hand, is a reminder not about actions - the performance of mitzvot - but about teachings, about belief. Belief is the basis of action. Of course Judaism emphasizes the importance of doing, of performing the mitzvot. Abraham Joshua Heschel once said that for Christianity the important thing was a leap of faith, but for Judaism it was a leap of action. For us faith without action is meaningless. But action without belief is hollow. As Solomon Schechter pointed out in his classic essay "The Dogmas of Judaism," there is no such thing as a religion without basic beliefs. Judaism, he wrote, "regulates not only our actions, but also our thoughts... a life without guiding principles and thoughts is a life not worth living." In Judaism, as opposed to some other religions, it is not always easy to come up with an exact formulation of what our dogmas are. Even Maimonides's famous 13 principles, for example, were not universally accepted as necessary beliefs. Nevertheless, one cannot be considered a religious Jews unless one has at least a modicum of belief. The Torah seems to be saying that that modicum is the affirmation of existence of the one God - the Lord - whom one is to love and serve wholeheartedly. That is what the mezuza contains and symbolizes. That is why the mezuza on our door is important in a way that far exceeds the superstitious beliefs that have become attached to it and have degraded it into a mere amulet. The writer is the head of the Rabbinical Court of the Masorti Movement and the author of several books, the most recent being Entering Torah.