The Bible describes in great detail the animal donations on the altar.
A person in the modern world sincerely does not understand why God can be pleased with the killing of innocent animals in order to propitiate God for human sins. This is difficult for a modern person to understand.
As early as the beginning of the Bible, we see that animal sacrifice was a human initiative.
When it was time for the harvest, Cain presented some of his crops as a gift to the LORD. Abel also brought a gift-- the best of the firstborn lambs from his flock. The LORD accepted Abel and his gift,( Genesis 4:3-4 )
God did not accept the sacrifice from the fruits of the earth, not because of the contents of the sacrifice, but because of Cain himself, who offered it. Note that Cain offered just some of the fruits he got, while Abel offered the firstborn, which is the best of what he had. See what God said to Cain in response to his anger:
You will be accepted if you do what is right. But if you refuse to do what is right, then watch out! Sin is crouching at the door, eager to control you. But you must subdue it and be its master."( Genesis 4:7 )
God did not ask for any sacrifices, animal or produce. God conveyed his true attitude towards sacrifice through a prophet named Ezekiel.
I gave them over to worthless decrees and regulations that would not lead to life. I let them pollute themselves with the very gifts I had given them, and I allowed them to give their firstborn children as offerings to their gods-- so I might devastate them and remind them that I alone am the LORD.( Ezekiel 20:25-26 )
Many people willingly killed innocent animals just so that God would "forget" about their own sins. People did not notice the pain of animals, placing the forgiveness of their sins above the pain of the innocent. When they offered sacrifices, people did not repent of their sins.
My hands have made both heaven and earth; they and everything in them are mine. I, the LORD, have spoken! "I will bless those who have humble and contrite hearts, who tremble at my word. But those who choose their own ways-- delighting in their detestable sins-- will not have their offerings accepted. When such people sacrifice a bull, it is no more acceptable than a human sacrifice. When they sacrifice a lamb, it's as though they had sacrificed a dog! When they bring an offering of grain, they might as well offer the blood of a pig. When they burn frankincense, it's as if they had blessed an idol.( Isaiah 66:2-3 )
By allowing people to sacrifice animals for their sins, God wanted to show the seriousness of our sins, for which we have to pay with blood... But the decision to sacrifice belongs to people who did not understand the true desires of God.
Should we offer him thousands of rams and ten thousand rivers of olive oil? Should we sacrifice our firstborn children to pay for our sins? No, O people, the LORD has told you what is good, and this is what he requires of you: to do what is right, to love mercy, and to walk humbly with your God.( Micah 6:7-8 )
They did not understand the obvious truth - no sacrifices and gifts to God can remove our sins or cleanse our consciences. The blood of the victims has been shed from generation to generation.
This is an illustration pointing to the present time. For the gifts and sacrifices that the priests offer are not able to cleanse the consciences of the people who bring them.( Hebrews 9:9 )
But instead, those sacrifices actually reminded them of their sins year after year. For it is not possible for the blood of bulls and goats to take away sins.( Hebrews 10:3-4 )
So, the people chosen by God did not repent when they saw the blood of innocent animals that was shed for their sins. Instead of asking for forgiveness, they chose a path in which their sins would be atoned for with the blood of another.
Seeing that people did not repent, seeing the blood of animals shed for their sins, God sent his own son into the hands of people to a certain and painful death.
" 'What will I do?' the owner asked himself. 'I know! I'll send my cherished son. Surely they will respect him.' "But when the tenant farmers saw his son, they said to each other, 'Here comes the heir to this estate. Let's kill him and get the estate for ourselves!'( Luke 20:13-14 )
As we know from the Bible, the priest first offered a sacrifice for his sins, and then only he could offer a sacrifice for the sins of the people. Jesus was sinless, and he did not need to sacrifice for his sins. Also, Jesus did not want the blood of innocent victims, and instead sacrificed himself, completely following the will of God.
Unlike those other high priests, he does not need to offer sacrifices every day. They did this for their own sins first and then for the sins of the people. But Jesus did this once for all when he offered himself as the sacrifice for the people's sins.( Hebrews 7:27 )
With his own blood-- not the blood of goats and calves-- he entered the Most Holy Place once for all time and secured our redemption forever.( Hebrews 9:12 )
And all this cruelty of sacrifices, which we attribute to God, actually lies with us and our sins.
It remains for us to think about how to accept the sacrifice of Jesus for our sins. If we do not confess our sins, then we reject his sacrifice as unnecessary for us, along with the salvation. If we confess our sins, then we understand that we are also guilty of the death of the son of God. As if we were sinless, then Jesus would not need to die ...