Some explanations you might have heard before:1) Because Cain's offering is not of firstfruit;
2) God loves keepers of sheep instead of workers of the ground;
3) Because Hebrews11:4 tell us Abel had faith.
Challenges to these explanations:1) Cain's offering can not be defined as an offering. At Cain's time, God had not enlightened them about the Five Offerings in the book of Leviticus.
2) There's just simply no Bible ground of this explanation.
3) This statement is true! Abel had faith. But Hebrews11:4b also said: "through which he was commended as righteous, God commending him by accepting his gifts." It is clear that God accepted Abel because of his offering. Through Abel's offering, God commended him as righteous. Thus, it is not just about faith, it is also about the object of faith.
The story of Abel and Cain happened right after the Lord God sent Adam and Eva out from the garden of Eden. Why is this story so important and what does this story tell us? Let us dig into and you will see this story is the foreword of the bible and the prophecy of human history and God's salvation!
Two Reasons(Hebrews11:4): 1) A blood sacrifice; 2) Faith
1. Cain's offering was not based on a Divine precept or principle.
At Cain's time, God had not enlightened them about the Five Offerings in the book of Leviticus. Cain's offering can not be defined as an offering. “Without shedding of blood is no remission” (Hebrews 9:22); “the blood of Jesus Christ his Son cleanseth us from all sin” (1 John 1:7); and “being now justified by his blood, we shall be saved from wrath through him” (Romans 5:9). The slaying of the lamb (“flock”) spoke strongly of the Lamb of God “slain from the foundation of the world” (Revelation 13:8), and “the Lamb of God which taketh away the sin of the world” (John 1:29). Cain’s offering did not foreshadow Christ at all; there was no lamb, hence no blood, no Christ, no cross. 1
But Abel's offering was based on a Divine revelation. Genesis 3:21 "And the Lord God made for Adam and for his wife garments of skins and clothed them." There was a life sacrificed for Adam's and Eve's sin. The first sin offering was made by God, the only effective way that we could use to cover our sins. And this sacrifice foreshadowed Jesus Christ. That is why Hebrews 11:4 said: "through which he was commended as righteous, God commending him by accepting his gifts." God accepted Abel simply because God accepted Jesus Christ.
2. By faith, Abel accepted the Divine revelation.After Adam sinned, "And the Lord God made for Adam and for his wife garments of skins and clothed them. (Genesis 3:21) A life was sacrificed because of their sin and this could calm God's anger. Adam learned from it and kept doing it, offering a blood-sacrifice, for the rest of his life.
Thus, Abel learned the way to cover his own sin from his father Adam. And by faith, Abel accepted and practiced it throughout his life. Genesis4:2b "Now Abel was a keeper of sheep." Why was Abel a keeper of sheep? At his time, people had not started to eat meat yet! People started to eat meat since Noah. (Genesis9:3) Abel was shepherding because he needed to offer a sacrifice to God regularly.
By faith, Abel put a blood-sacrifice, which foreshadowed Jesus Christ, between God and himself. This is the salvation of God's revelation through the Bible. This salvation can save sinners because it is from God and is done by God. The only thing we have to do is to accept it by faith. That is why Hebrews11:4a said: "By faith Abel offered to God a more acceptable sacrifice than Cain..."
In the story of Cain and Abel, we can see God's salvation right after Adam's fall! Amen! There are two things in God's salvation: 1) a sacrificed life for our sin - Jesus Christ; 2) the faith to accept this sacrifice.
No doubt reason might say, what more acceptable offering could a man present than that which he had produced by the labor of his hands and the sweat of his brow? The reason, and even man’s religious mind, may think thus, but God thinks quite differently; and faith is always sure to agree with God’s thoughts. God teaches, and faith believes, that there must be a sacrificed life, else there can be no approach to God.2
The story of Cain and Abel is the story of us! One believes and the other one rejects. When Jesus was on the cross, one of the criminals who were hanged railed at him, saying, “Are you not the Christ? Save yourself and us!” (Luke23:39) But the other said, “Jesus, remember me when you come into your kingdom.” (Luke23:42) Like Cain and Abel, there are only two kinds of person: one accepts God’s sacrifice (Jesus Christ) by faith and one does not. And what behind this are two things: 1) a blood sacrifice – Jesus Christ; 2) the faith.
Butler, John G. Heroes: The Biography of Faith (Hebrews 11). Vol. Number Twenty-Seven. Bible Biography Series. Clinton, IA: LBC Publications, 2008.
Mackintosh, C. H. Genesis to Deuteronomy: Notes on the Pentateuch. Neptune, NJ: Loizeaux Brothers, 1972.