As the Torah describes the sacrificial service, it says that when the smoke of the offering rises to heaven, it will be a "soothing aroma to the LORD" (Leviticus 1:9). Rashi interprets the "soothing aroma" as a metaphor for man's obedience. He explains that the aroma of the sacrifice is pleasing to the LORD because it is a token of His children's obedience. When God "smells" the sacrifice, He delights in the human being who has gone to such effort to draw close to Him.
Regardless of how we understand it, the Torah is clear that God takes delight in the sacrifices. He graciously accepts the gifts of His people, and the smoke that rises from the altar fires is as a soothing aroma to Him.
This seems difficult to reconcile with many statements in the prophets where God speaks out against the sacrifices. For example, in the book of Isaiah He says, "I have had enough of burnt offerings of rams and the fat of fed cattle; and I take no pleasure in the blood of bulls, lambs or goats ... bring your worthless offerings no longer" (Isaiah 1:11-13). Likewise, in the book of Jeremiah He says, "Your burnt offerings are not acceptable and your sacrifices are not pleasing to Me" (Jeremiah 6:20). In the book of Malachi He says, "[If only] you might not uselessly kindle fire on My altar ... nor will I accept an offering from you" (Malachi 1:10).
In the early days of Christianity, the church fathers often cited texts like these to try to prove that God had never wanted the sacrificial system. Some used these and similar passages to suggest that God had given the sacrifices to the Jews as a punishment. They argued against the Jewish people, claiming that Jesus had done away with the sacrifices because God had always hated them.
That does not make sense. If God always hated the sacrifices, why did He command the children of Israel to bring them in the first place? Why did He state over and over that He was pleased with them?
A better explanation comes from a more careful reading of the prophets. When the prophets seem to speak against the sacrificial system, they are not condemning the mode of worship, they are condemning the worshippers. In every instance the prophetic rebuke is directed toward the immoral, disobedient people among the Israelites who were violating the covenant of Torah while continuing to go through the motions of the sacrificial system. Though their hearts were far from God, they continued to perform their religious rituals.
This can be compared to a wicked womanizer who beats his wife and cheats on her but continues to faithfully attend church every Sunday and take communion with the rest of the congregation. The religious ritual is meaningless and an insult to God. Or suppose the same fellow, after beating his wife and cheating on her, dutifully sends her a bouquet of roses. Would she be pleased to receive the flowers? Hardly. She would say, "Your flowers are an abomination to me!" In the same way, God hates religious rituals when they are performed hypocritically.
These lessons should be a warning to all of us. We must be careful not to develop any sense of right standing with God because of ritual observances. God is interested in the state of our hearts. Our outward rituals should reflect our inward conditions.