Genesis 4 has always bothered me. The story of God accepting Abel's sacrifice and not Cain's has led me to wonder: How did they even know to sacrifice? Was this practice started by Adam? Or did God establish more of a law than just 'Don't eat of the tree of the knowledge of good and evil'? If God did establish further law then what was it and when did He establish it?
That's a very good question. Clearly there are a lot of details missing from the earliest parts of the narrative. Remember that Genesis is traditionally attributed to Moses, who led the Israelites out of Egypt and gave them the Law of Moses. Storytellers tend to explain unfamiliar concepts and not waste time explaining familiar ones, so it's reasonable to infer that Adam and his family were under a commandment from God to offer sacrifices in a similar, if not identical, manner to the rules about sacrifices in the Law of Moses. Beyond that, the Bible is unfortunately silent.
God told them to do it.
That is what the student has to assume because of later revelation.
We also for example in reference to the fall, assume that either God told Eve "neither shall you touch it." Since there is no record of God forbidding "touching" the tree of the knowledge of good and evil. We assume either Eve was commanded by God to not touch the fruit, or Adam forbade touching. Because any other observation other than this assumption makes sin existent in Eve before the eating, thru lying.
Thus we can assume that animal sacrifice was introduced to them but God chose not to give the details about it. Keep in mind that from Eden to the flood and Babel there was a tremendous amount of world activity. But God limits our exposure to this time period to just 11 chapters.
The necessity of blood was a lesson soon learned by the sons of the first human couple. The time came for both Abel and Cain to bring their sacrifices before God (Gen. 4:3-16). Cain offered for sacrifice the fruit of his labors in the field. The offering was vegetable, and it was bloodless. Abel brought a blood-offering taken from his flock. When God passed judgment on the two types of offerings, that of Cain was rejected, and that of Abel was accepted. So a lesson was taught: One cannot approach God by whatever means one chooses. It is man who sinned and offended the holy God; it is God who must do the forgiving. Therefore, it is not for man to choose the means of forgiveness, but for God, and God has chosen the means to be blood. Cain had chosen to approach God in his own way, but he was rejected. Abel chose the way God demanded, and his sacrifice was accepted.
As biblical history develops in the Book of Genesis, we find that all the ones with whom God was pleased came to Him by means of blood. Noah immediately offered up blood sacrifices when he left the ark. He was followed by other great men in Jewish history: Abraham, Isaac, and Jacob, all of whom were careful to approach God by means of blood. When Moses received the Law at Mount Sinai, the redemptive element of blood ran throughout the entire Law with its 613 commandments.
A great summary statement for the entire Law is found in The Third Book of Moses, Leviticus 17:11: For the life of the flesh is in the blood; and I have given it to you upon the altar to make atonement for your souls: for it is the blood that makes atonement by reason of the life. It can easily be said that all of the Law revolves around this one statement. There were commandments which God gave in the Law that were to be obeyed. Disobedience was sin. If disobedience did take place, the means of atonement for the sin was blood. The Book of Leviticus opens by giving great detail to the different types of blood-sacrifices. All of these different sacrifices had the same purpose: that the Jew might be rightly related to God.
All seven feasts of Israel: Passover, Unleavened Bread, Firstfruits, Pentecost, Trumpets, Day of Atonement, and Tabernacles required the shedding of blood. The Yom Kippur or Day of Atonement ceremony was greatly detailed in Leviticus 16, where careful instructions are given for the shedding of blood to atone for the sins of the Jewish nation. The Tabernacle and the Temple both were built to expedite and to make efficient the required shedding of blood for the atonement of the people's sins. The Holy of Holies that contained the Shechinah Glory, the visible manifestation of the presence of God, could be entered only once a year by only one man, the high priest. In order for him to enter, he had to have the blood of the Yom Kippur sacrifice with him, and this blood had to be sprinkled on the Ark of the Covenant, which contained the tablets of the Law itself.
This is detailed in Leviticus 16:15-17: Then shall he kill the goat of the sin-offering, that is for the people, and bring his blood within the veil, and do with his blood as he did with the blood of the bullock, and sprinkle it upon the mercy-seat, and before the mercy-seat: and he shall make atonement for the holy place, because of the uncleannesses of the children of Israel, and because of their transgressions, even all their sins: and so shall he do for the tent of meeting, that dwells with them in the midst of their uncleannesses. And there shall be no man in the tent of meeting when he goes in to make atonement in the holy place, until he come out, and have made atonement for himself, and for his household, and for all the assembly of Israel. And so the principle stood throughout the remainder of Old Testament history . But it was a burden to the individual. These blood-sacrifices had to be repeated year in and year out and they had to be done in the Temple at Jerusalem. For the Jews living elsewhere in the country , miles from Jerusalem, it was a burden to come every year to offer their sacrifices to the Lord for the atonement of their sins. Only the faithful few , those whom the prophets referred to as the Remnant, loved God and His Law enough to do so in spite of the burden it created.
Others built their own altars on mountains and hills closer to home and offered their sacrifices there. But no atonement was granted at these rival altars, and the prophets of God railed against these practices and condemned this deviation from the Law of God. Many had failed to learn the lesson of Cain: that one cannot come to God for forgiveness in any way one may choose, but one must come in the way God Himself has chosen.
It was Isaiah the Prophet who first provided the hope that the day would come when the yearly burden would be lifted. In Isaiah 53, God declared that the Suffering Servant, the Messiah, would be the sacrifice for sin.
In Isaiah 53:10-11 we read: Yet it pleased Jehovah to bruise him; he has put him to grief: when you shall make his soul an offering for sin, he shall see his seed, he shall prolong his days, and the pleasure of Jehovah shall prosper in his hand. He shall see of the travail of his soul, and shall be satisfied: by the knowledge of himself shall my righteous servant justify many; and he shall bear their iniquities. The point of Isaiah 53 is basically this: the animal sacrifices under the Mosaic Law were intended to be of temporary duration, a temporary measure only. God's intent was for there to be one final blood-sacrifice and that would be the sacrifice of the Messiah Himself.
That is why Isaiah 53 uses the same type of wording, figures and emphasis found in the Book of Leviticus. For example, in verse 10b we have the expression: you shall make his soul an offering for sin.
This is a sacrificial concept; these are words that come out of the Mosaic Law itself.
And in verse 11b we read: by the knowledge of himself shall my righteous servant justify many; and he shall bear their iniquities. Not only are these words of sacrifice used generally in the Old Testament Law, but more specifically , we read of these very terms in Leviticus 16, which is the chapter that expounds and explains all the details regarding the Yom Kippur or Day of Atonement sacrifice.
This, then, was the reason why Messiah had to die: to provide the blood-sacrifice for sin once and for all. No longer would the Jews be burdened with the yearly sacrifices. All a person would need to do is accept the Messiah's death on his behalf and his sins are forgiven. Messiah had to die in order to provide that atonement, for blood is the means of redemption.
Another key issue is found in these two verses from Isaiah 53. There is a statement here that is somewhat confusing. Verse 11b reads: by the knowledge of himself shall my righteous servant justify many. A more literal translation from the Hebrew text would read like this: “the knowledge of him shall my righteous justify many.”
The word for knowledge is a Hebrew word that emphasizes experiential knowledge, not mere head knowledge. This is a knowledge of the heart or a knowledge of faith. Those who have a faith-knowledge of this Servant, by “the knowledge of him,” that He died for our sins, not by the knowledge of himself, He will, as a result, justify us. Justification means, “to be declared righteous.” We cannot be declared righteous unless our sins have been atoned for. Our sins can only be atoned for by the shedding of blood; the Messiah's blood would be the final blood that would be sacrificed.
Perhaps animal life sacrifice was begun by God himself in:
All Scripture is quoted from the King James translation, unless otherwise noted.
Cain and Abel would have been familiar with this since an animal would also have to be sacrificed to make clothing for them, and at that time they were vegetarian, so there would have been no skins left from their food to make clothes for them.
There is probably no connection between Cain's giving of vegetation since he was the one who tilled, while Abel was the tender of the flock. Each was giving the fruits of their labor.
Since both were old enough to labor it is probable that many animals had been sacrificed to provide clothing for the whole family, and so animal sacrifice would already be somewhat justified in protecting them from the elements, and to hide their nakedness.
Also although it is not mentioned prior to this it is most likely that Adam and Eve had produced daughters by this time.
A little math tells that the death of Abel took place sometime between Adam's creation and 130 years when Seth was born.
Hope this helps.
A view that I osculate is that Abel knew the prophecy in Genesis 3:15 (NIV) which says:
He likely had given much thought to that promise and believed that blood would have to be shed, someone would have to be ‘bruised in the heel,’ so that mankind might be uplifted again to the state of perfection that Adam and Eve had enjoyed before their rebellion. (Hebrews 11:4)