Hashem said to Moshe and Aharon, "Because you did not believe in Me to sanctify Me in the eyes of the Children of Israel, therefore, you will not bring this congregation to the land that I have given them (Bamidbar 20:12).
What precisely was the sin of Moshe and Aharon? This elusive question has engaged the greatest of our commentators throughout the generations. The Ohr Hachaim Hakadosh catalogues ten different answers to this vexing question. Rambam offers a novel answer to this question which he describes as "one of the most difficult in the Torah". The ensuing remarks are devoted to Rambam's novel interpretation.
In the fourth of the Eight Chapters, and subsequently in Hilchos De'os, Rambam develops the doctrine of moderation. We are commanded to avoid extremes and cultivate the mean. Thus, by way of illustration, one shouldn't eat gluttonously, but neither should he neglect basic nutritional needs. The mean in this instance consists of eating to maintain one's health and strength.
Against this background, Rambam explains that Moshe [and Aharon] sinned in deviating from the mean, and becoming angry with the Jewish people and manifesting their anger by addressing the people as "rebels".
Ramban sharply critiques this Maimomidean explanation. Inter alia, he argues that the pesukim do not accommodate Rambam's intepretation. As quoted above, Hashem faults Moshe and Aharon for not believing. According to Rambam's analysis, however, their sin was unrelated to a lack of faith.
Let us explore the Rambam's doctrine of the mean. In Hilchos De'os, Rambam explains that this doctrine is mandated by the mitzva of v'holachto b'drachav (imitatio dei). Hashem's actions are all balanced, and thus the mitzva of imitatio dei commands that we behave in a similar fashion.
The identification of v'holachto b'drachav with the mean generates a remarkable, highly repercussive corollary. Since our behavior is commanded and thus (at least, in the case of righteousJewish leaders) presumed to be godlike, our actions reflect upon Hakadosh Baruch Hu. Hence if we display anger, we eo ipso insinuate anger to Hakadosh Baruch Hu.
Thus, Rambam concludes his exposition of Moshe's sin as follows.
So, when Moshe said or did anything, [the Jewish people] subjected his words or actions to the most searching examinations. Therefore, when they saw that he waxed wrathful, they said, "He has no moral imperfection, and if he did not know that God is angry with us for demanding water and that we have stirred up the wrath of God, he would not have been angry with us." However, we do not find that when God spoke to Moshe about this mater He was angry.
Accordingly, the phrase, "because you did not believe in Me" should be understood, according to Rambam, that your actions bespoke a lack of faith because they projected an unbalanced, distorted image of Hakadosh Baruch Hu. Faith involves not only correct beliefs regarding Hakadosh Baruch Hu, but also equally correct projections of His image.
Faith must be reflected in all our words and deeds, and in all realms. When rachmana litslan our words or deeds are flawed, eo ipso our faith is deficient.