The Purpose of Matan Torah – Emunah
The Aseres HaDibros begins with וידבר אלקיך 'ה אנכי ,לאמר האלה הדברים כל את אלקים. Rebbe Elimelech of Lizhenzk zt'l said we should translate these words as follows: Hashem taught האלה הדברים כל, the entire Torah so a Yid will be able to say אלקיך 'ה אנכי. In other words, the purpose of matan Torah and all the mitzvos is so that we will believe in Hashem.
A hint to this idea is found in the shemoneh Esrei of Rosh Hashanah, where it says ובתורתך אחד 'ה אלקינו 'ה ישראל שמע לאמר כתוב. This can be translated as "Everything that is written in the Torah is so people will be able to say 'Hashem is our G-d Hashem is one.'" That is the segulah of Torah and mitzvos; it fills our hearts with emunah in Hashem.
On a similar note, the Vilna Gaon zt'l (Mishlei 22:19) writes, בכדי הוא לישראל התורה נתינת עיקר 'בה בטחונם שישימו, "The Torah was given, primarily, so that the Jewish nation will have bitachon in Hashem."
Rashi (Devarim 4:35) writes, "When Hakadosh Baruch Hu gave the Torah to Bnei Yisrael, He opened up the seven heavens...and all the lower worlds, and they saw that there is only Hashem. As it states, 'ה כי לדעת הראת אתה מלבדו עוד אין האלקים הוא, 'You were shown that Hashem is G-d, there is none other than Him.'"
This is the purpose of matan Torah: so we will know that Hashem is G-d; there is no other.
The Degel Machaneh Efraim (beginning of parashas Ekev) writes, "The main thing is emunah. My grandfather, the Baal Shem Tov zt'l, would emphasize the importance of emunah. Emunah is the basis of avodas Hashem and the foundation of the Torah. Dovid HaMelech said (Tehillim 119:86) אמונה מצותיך כל, 'All your mitzvos are about emunah.'"
The Ramban (end of parashas Bo) also tells us that emunah is the foundation of the Torah. He writes, "If one doesn't believe that everything that happens to us is miraculous... he doesn't have a portion in the Torah."
The Rishonim ask why the Aseres HaDibros says, "I am Hashem, your G-d Who took you out of Mitzrayim." It seems more appropriate and significant to say, "I am Hashem, your G-d, Who created heaven and earth!" But there is a lesson in yetzias Mitzrayim that we don't know from creation. Yetzias Mitzrayim tells us that Hashem continues to lead the world with hashgachah pratis!
The Rosh (Orchos Chaim ו"כ 'א יום) writes, "Trust in Hashem with all your heart. Believe in His hashgachah pratis... Believe that Hashem sees everything. He sees everything you do and examines your heart and your thoughts. Whoever doesn't believe in yetzias Mitzrayim [hashgachah pratis] also doesn't believe in אלקיך 'ה אנכי [belief in Hashem]... These beliefs make us the chosen nation and are the foundation of the entire Torah." Thus, the Rosh reveals that yetzias Mitzrayim teaches hashgachah pratis, which is a primary foundation of emunah.
