The book of Vayikra opens by saying "ויקרא אל משה וידבר ה' אליו...", indicating that Hashem called Moshe and then spoke to him (ויקרא א:א). The Midrash asks, "למה הקדים קריאה לדיבור", why was it necessary to first call Moshe before speaking to him? Chazal respond that the Torah was looking to teach proper manners and דרך ארץ, instructing that one shouldn't go speak to his friend unless he has been called. From here Chazal add, we may derive that "תלמיד חכם שאין בו דעה נבלה טובה הימנו" a Talmid Chacham who does not know how to behave properly is worse than a dead animal.
Rav Michel Birnbaum, in his שיחות מוסר, accentuates the profound message of this Midrash. Moshe Rabbeinu personified the epitome of wisdom; he was the אבי הנביאים, the greatest of all prophets. He guided the Jews from bondage, was instrumental in the miraculous events in Egypt and at the Red Sea, climbed to the heavens and returned with our Holy Torah, and diligently supervised the construction of the Mishkan. Yet even he could enter the Ohel Moed, where Hashem dwelled, until he was summoned. If Moshe Rabbeinu had suddenly entered unannounced, his outstanding accomplishments and his remarkable devotion to Hashem wouldn't have sufficed to spare him from being identified as a תלמיד חכם שאין בו דעה, a scholar who does not know how to behave. Clearly, genuine dedication to Yiddishkeit and proper Middos are inextricably bound together and are both necessary in order to observe the will of Hashem. Without adhering to the lessons of Mussar, one Mitzvos cannot perform the best of the Mitzvos properly.
This powerful lesson may also be derived from an important detail in the story of Creation. When He was about to create Man, Hashem stated "נעשה אדם בצלמנו...," meaning, let us make man in our image (בראשית א:כ"ו). All the Meforshim are troubled by the use of the plural form here, since Hashem alone created Man; Rashi suggests that Hashem was consulting with the angels. Obviously, Hashem did not need the angels to assist Him in the creation of Man. Rather, he says, the Torah is teaching us an important message about humility. If Hashem Himself saw fit to consult with the angels about the creation of Man, everyone, even the greatest individuals, should seek advice from others that may not appear to be as wise as they are.
However, Rashi himself alludes to a difficulty with this explanation. By writing the plural form "נעשה," let us make, the Torah is exposing itself to an attack from the unfaithful. Heretics might claim that Hashem is not all-powerful and needs help from others (ח"ו). Wouldn't it have been wiser to avoid such a great risk by injecting ethical teachings such as this into other parts of the Torah, where they would not raise such difficulties? The Alter of Slabodka explained that Middos Tovos are a prerequisite for belief in Hashem. Those whose faith is not rooted in Mussar and ethical teachings cannot properly believe in Hashem. The Torah was thus willing to leave itself vulnerable to misconceptions in order to emphatically declare right at the outset, when describing the beginnings of Mankind, that Emunah which is lacking in דרך ארץ will not endure.
There are many Mitzvos in the Torah which are difficult to understand, and often remain unexplained. The Mitzvos relating to Korbanos fall into this category, but the Meforshim nevertheless have all found it necessary to at least attempt to explain the meaning of Korbanos. This is probably because the Korbonos are easily misunderstood. The common translation of the word Korban to mean sacrifice is the best indication of how far away the usual understanding is from the actual concept communicated by the word. The root of the word קרבן is קרב meaning near, which has very little relationship to the concept of sacrifice as it is generally understood.
In an attempt to show how the Torah's conception of sacrifices was not like that of the pagan religions, the Rambam tells us that the Torah wished to educate people away from idol worship. The Rambam is often misquoted as saying that the Mitzvah to bring Korbanos was a concession to ancient practices and the Torah permitted this only because ancient Israel would have sacrificed animals anyway, even had the Torah not sanctioned this. However, this is not really what the Rambam says. Rather, he explains that in ancient times, cattle were often considered to be sacred animals, as they are today in certain countries like India. The Torah, therefore, instructs us to slaughter these animals in our worship of Hashem, in order to demonstrate that these commonly worshipped animals have no power whatsoever.
The Ramban disagrees with the Rambam, noting that the idea of קרבנות was known even to the earliest men, Kayin and Hevel. They used it as both a method of expression of appreciation of Hashem and His Divine goodness, and as a symbolic representation of the atonment of a sinner, by allowing the animal to take the place of the sinner. These are, therefore, the underliying roots of Korbanos and their basic meaning.
Rav Shimshon Raphael Hirsch, in his commentary on Vayikra, explains the Korbanos as being symbolic of the loftiest goals of spirituality (רוחניות). His writings explain how each element of the process of offering a Korban is an expression of Divine service to Hashem. It is only through these explanations and others like them that it can be possible to understand why Chazal have said that it is prayer and not charity that replaced the Korbanos after the destruction of the Beis HaMikdash, because proper prayer encompasses all of these same concepts.