3 ¶ And in process of time it came to pass, that Cain brought of the fruit of the ground an offering unto the LORD. 4 And Abel, he also brought of the firstlings of his flock and of the fat thereof. And the LORD had respect unto Abel and to his offering: 5 But unto Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell.
The process of time is used several times in the Bible to indicate the passage of time. For instance, 2Chronicles 21:19 begins with, And it came to pass, that in process of time, after the end of two years.
Cain gave a plant offering, a vegetable or fruit offering, to God, as the Hindus do today in the Prasada, a vegetable offering to a god. It is important to them that their god accepts only a strict vegetable offering, so that nothing experiences pain or suffering. Prasada means mercy in Sanskrit, the grace of the god they invoke.
Abel offered up the firstling of his flock. Something living was sacrificed and died. Blood was shed. The issue here is this;
Hebrews 9:22 And almost all things are by the law purged with blood; and without shedding of blood is no remission.
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 an atonement for your souls: for it is the blood that maketh an atonement for the soul.
There is no remissions of sins, no forgiveness for sins, without the shedding of blood. Animal sacrifices, as clearly animals are important to God, were substitutions for His own flesh which He sacrificed on the Cross at Calvary and His own blood which He shed for our sins.
Acts 20:28 Take heed therefore unto yourselves, and to all the flock, over the which the Holy Ghost hath made you overseers, to feed the church of God, which he hath purchased with his own blood.
Ephesians 5:2 And walk in love, as Christ also hath loved us, and hath given himself for us an offering and a sacrifice to God for a sweetsmelling savour.
Hebrews 9:12 Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtained eternal redemption for us.
Hebrews 13:12 Wherefore Jesus also, that he might sanctify the people with his own blood, suffered without the gate.
Revelation 1:5 And from Jesus Christ, who is the faithful witness, and the first begotten of the dead, and the prince of the kings of the earth. Unto him that loved us, and washed us from our sins in his own blood,
And here, very clearly, regarding the law given to Moses;
Hebrews 10:1 ¶ For the law having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect. 2 For then would they not have ceased to be offered? because that the worshippers once purged should have had no more conscience of sins. 3 But in those sacrifices there is a remembrance again made of sins every year. 4 For it is not possible that the blood of bulls and of goats should take away sins. 5 Wherefore when he cometh into the world, he saith, Sacrifice and offering thou wouldest not, but a body hast thou prepared me: 6 In burnt offerings and sacrifices for sin thou hast had no pleasure.
Animal sacrifices were a remembrance and an acknowledgement of the sinful state of mankind. But, God Himself put our sins away from us so that we would neither be held accountable for them nor would we have to bring them to remembrance at established times. This possibility was hinted at in the Old Testament;
Psalm 103:12 As far as the east is from the west, so far hath he removed our transgressions from us.
Read Revelation 1:5 above again. God did not regard Cain’s offering but He did regard Abel’s. This made Cain angry, but did not lead him to repent and do what God demanded. This reminds me of the religionist today who will not so much as even acknowledge his own sinful state but insists that reciting such things as The Lord’s Prayer, taking communion, or rushing to the church building whenever the doors are open should be good enough to justify himself or herself before God. I’ll do it my way, they think in their hearts, and you ought to accept me because of my effort. We Christians, because of Christ, do not offer animal sacrifices, but are to offer sacrifices pleasing to God in regard to His sacrifice of Himself, Christ.
Psalm 141:2 Let my prayer be set forth before thee as incense; and the lifting up of my hands as the evening sacrifice.
Hosea 14:2 Take with you words, and turn to the LORD: say unto him, Take away all iniquity, and receive us graciously: so will we render the calves of our lips.
Hebrews 13:15 By him therefore let us offer the sacrifice of praise to God continually, that is, the fruit of our lips giving thanks to his name.