In Parshas Vayikra we begin to read of the korbanos (sacrificial service). As we have discussed previously, the korbanos are an expression of one of the most basic concepts of Judaism, that there is no activity, no matter how mundane or physical, that cannot be lifted up to the service of God. Even as mundane an activity as slaughtering, butchering, cooking, and eating an animal can truly bring us closer to God, as implied by the term korban, if done with the proper intention, in compliance with God's commands.
Indeed, the spiritual power of the korbanos is not, ultimately, rooted in the actions themselves, but in the fact that they are done in obedience to God's will. As the prophet Samuel said to King Saul (I Samuel 15:22), "Does God want burnt-offerings and sacrifices as much as obeying the voice of God? Behold, to obey is better than sacrifice, and to hearken than the fat of rams."
This is actually true for all the mitzvos. While there is no question that the mitzvos serve a variety of functions, including teaching us important spiritual lessons, the basic function of the mitzvos is to bring us closer to God, and this can only be achieved through fulfilling God's commands.
One of the classic difficulties in religious philosophy is understanding how it is possible for a human being - a finite, limited, physical being - to achieve a true connection and unity with a God Who is infinite and incomprehensible. Judaism teaches that it is the mitzvos - the commandments - that enable us to achieve this otherwise impossible union. When God commands us to perform a given act, no matter how physical that act may superficially appear, He has invested that act with His Will. Thus, when we perform that physical act, we achieve a connection with the Will of God.
We say in the Shema, “Hashem Echad”—“God is one.” This basic principle of Judaism, the absolute unity of God, tells us that God is absolutely indivisible; He and His Will are one. When, through the performance of a mitzva, we achieve a connection with the Will of God, we are connecting to God Himself. This is only possible because God has connected the given act with His Will. This is the essence of the mitzva concept. An act that is not commanded by God, as positive as it may be, is ultimately a finite act that cannot, in of itself, achieve devekus—true union with God. Thus, many commentaries connect the word mitzvah with the Aramaic term “tzavsa” – “binding” – because the mitzvah binds us to God, precisely by virtue of the fact that it is a mitzva.
When one brings a korban in accordance with Torah law, one is implicitly declaring his acceptance of the authority of the Torah and his commitment to obey all of God's commandments, even those which, like the korbanos, are essentially non-rational. It is this commitment which gives the korbanos their power to atone for sin and to bring us closer to God. Indeed, the commentaries tell us that the reason the Torah calls a korban a “satisfying aroma to Hashem” (Leviticus 1:9) is that just as our sense of smell can detect a scent from a distance, similarly when a person brings a korban, it hints to the good deeds and the spiritual improvements that the person will do in the future. It gives a “pleasing aroma” of his future mitzvos. This is the "satisfying aroma" that God “smells” when a person brings a korban. (Rav Eliezer Ashkenazi, cited by Rav Elie Munk in The Call of the Torah and חדושי הרי"ם, cited in מעינה של תורה)