Why was Cain's sacrifice rejected?

[Kevin]

God has just made a brand new earth. Everything is blissful. Not long after, man falls into sin and God devices a plan to rescue him. The first sacrifice is alluded to in Gen 3:21, where God slays an animal to fashion tunics of skin for Adam and his wife.
In Genesis 4, Cain and Abel are born and they bring their various offerings to the Lord. The Lord is delighted with Abel's offering but Cain's, not very much (Genesis 4:3-7). This is where my question comes; from Genesis 1, we have not seen a scriptural description of how the offering was to be done, yet Cain's offering is rejected.

1. Where were the standards of offering prescribed leading to the rejection of Cain's offering?
2. What are the implications of this case on our lives today?

 

[Chief]

In Genesis 4:3-7, "

"And in process of time it came to pass, that Cain brought of the fruit of the ground an offering unto the LORD. 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: but unto Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell. And the LORD said unto Cain, Why art thou wroth? and why is thy countenance fallen? If thou doest well, shalt thou not be accepted? and if thou doest not well, sin lieth at the door. And unto thee shall be his desire, and thou shalt rule over him."​

Here we see both brothers coming to worship God in a prescribed format, through offering of sacrifices. If God had prescribed a sacrificial system for them, He surely had laid out the details - including what ought to be sacrificed and how it was it was to be done. We can catch a glimpse of this in verse 7 when God tells Cain that sin lies at the door if he does not do well. We also know that sin is the transgression of the law (1 John 3:4), meaning that God had already set out a command on this very matter.

We can also see that Cain was wroth when his sacrifice was not accepted. Knowing that the wicked flee even though no one pursues them (Proverbs 28:1), we can conclude that Cain was condemned by his own conscience (1 John 3:20-24) because the spirit of God had already revealed to Him what He ought to have done but he chose not to do it. His greatest sin, therefore, was the sin of disobedience - see Hebrews 11:4. He knew that a sacrificial system required shedding of blood (God had already set precedence in Genesis 3:21 when He slew the lamb and made tunics for Adam and his wife). There is no remission of sin without shedding of blood (Hebrews 9:22-28), and the antitypical sacrificial system pointed to the ultimate sacrifice, Christ, who is the lamb of God that taketh away the sin of the world (John 1:29).

The implications of Cain's case for us today can be multifold. However, we should listen to the voice of God and do only His bidding because God wills to do good for us. His intentions are pure.