I don't buy the standard answer on this subject.
Seems worthy of discussion.
Let's explore some theories. Thanks.
The standard answer is that Abel's offering was a blood sacrifice.
I don't think that was the reason that Cain's offering was rejected.
They both brought something from the work of their hands.
Was Cain condemned for working the soil rather than keeping a flock?
The first lesson about the gospel of the kingdom of God for us His people is this topic, because this was the first case that happened in this perishable world.
The things we need to understand that in that time :
1 there was no complete scriptures like what we have at this time.
2 at that time there was no command to humans to offer anything to God.
3 until then, humans only knew that they were ordered such Gen. 3: 17-19.
Gen3:17 And unto Adam he said, Because thou hast hearkened unto the voice of thy wife, and hast eaten of the tree, of which I commanded thee, saying, Thou shalt not eat of it:
cursed is the ground for thy sake;
in sorrow shalt thou eat of it all the days of thy life;
3:18 Thorns also and thistles shall it bring forth to thee; and
thou shalt eat the herb of the field;
3:19
In the sweat of thy face shalt thou eat bread, till thou return unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou return
4 From 1,2,3 above, it can be concluded for awhile that when Abel became a shepherd of a sheep, nothing will be taken from the results of his pasture (both for himself and God).
From 1 to 4 above there is nothing that brings us to associate God's rejection of Cain's offerings triggered by the type of offering itself, nor does anything show the value of Abel's offering more than Cain so that God
must heed it.
We just found out finally when the scriptures said:
Gen4:4 ……. And the LORD had respect unto Abel and to his offering:
4:5 But unto Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell
So what was God's reason?
When we examine further from His Word:
1John3:12 Not as Cain,
who was of that wicked one, and slew his brother. And wherefore slew he him? Because his own works were evil, and his brother's righteous
Jud1:11 Woe unto them! for they have gone
in the way of Cain, and
ran greedily after the error of Balaam for reward, and
perished in the gainsaying of Core
From those two verses , we come to the estimate that the God’s reason was related to: the personality of Cain that was different from Abel in the eyes of God (from the Evil One/
of that wicked one, in connection with Balaam evil who wanted to curse the Israelites for reward greedily /to curse God’s chosen people,
Core who rebelled against Moses who is the prophet of God), these were also confirmed that since before the world was made God did have vessels of wrath Rom9: 22, and vessels of mercy Rom9: 23, here the Abel’s spirit was likened = God’s vessel of mercy =the chosen , Cain was
of that wicked one , prescribing that the spirit that lives in Cain's body was the
wicked one= the vessel of wrath = the devil himself.
So this topic seems clear that God would teach us about the existence of the chosen people and people in generally that was not the chosen = born of flesh people which in its development shall be the devil’s camp Gen3:14 =
vessels unto dishonor Rom9: 21 which in its development shall become a camp of the devil (vessels of wrath abode in to the vessels unto dishonor ) Rom9: 22 = Judas John 6: 70 = physical descendants of Abraham who became the camp of the devil John 8: 44 = tares Mat13: 38-39 = pigs that died in choked Mark 5: 12-13 = written in Mat23: 33 in stead of about offerings .
The lesson about the chosen people is very important because without a correct understanding of the existence of a chosen people in the eyes of God, God's people will not come to an understanding of the Christian faith, "Salvation is by God’s grace alone", this lesson continues to be repeated many times like Noah's flood. where His chosen people are only 8 persons beyond them were all afflicted by floods, they were devil’s camp/devil possessed (doomsday by water), and God had also promised that the end of nature will be a repetition of this event but by fire ( how can this world end if there are no people such them ? ), still about this lesson after the flood of Noah God scattered them in Gen. 11: 7-9 so there were many pupil and languages that could be chosen one among them as the physically chosen people , still about this lesson on Moses age, God distinguishes His people from common human beings (Ex 11: 5-7; Ex 33: 16; Josh 6: 21), and many more both in the OT and in the NT.