Cain And Able - Where Did The Blood Sacrifice Start?

Yesterday we talked about Cain and Able's Offering to God.  Lets look at this a little closer because there is a lot questions around these offerings.

• How did Cain and Able know to give a blood offering to God?

Lets go back to when Adam & Eve first sinned.  They were still in the garden of Eden.  They had eaten the fruit from the tree of knowledge.  After they ate this fruit, their eyes were opened and they knew they were naked. (this was the first effect of there sin. They were ashamed of their nakedness)   God knows what they have done and sees that they have used fig leaves to cover their nakedness.

• What does God do here and why?  Adam and Eve made an attempt to cover their sin with fig leaves.  This was not acceptable to God as a cover for their sin. So God shows them what he expected in order to be forgiven for their sin.  
• God makes the first Blood sacrifice recorded in the Bible.  He sacrificed a animal to make new skins for Adam and Eve to wear in order to cover their nakedness (their sin). From this act we know that not only does God tell us what he wants - He shows us what he wants.  (Later on he shows us more specifically what he wants from us through his son Jesus)

Lets remember that Cain and Able were grown men when they made their offerings to God.  More than likely they had made numerous offerings to God that was accepted before the one talked about in Genesis 4.  But for some reason Cain decided to disregard what God wanted and give something he wanted to give instead of what God wanted him to give.  Even though he disregarded what God expected of him, God still gave him another chance to redeem himself.  He then gets mad and lets his sin nature take over him so much that he kills his brother Able.

Why didn't God accept Cain's offering?  First God had commanded them to give blood sacrifice, we know this because he did this himself when he made Adam and Eves clothes to cover their sin & later own he makes it law for everyone to do this in order to be forgiven for their sins.(This of course was before Jesus Christ came and give himself as the blood sacrifice that will cover all of our sins)

Lets look at a real world example of debt & payment

God required a certain payment for sin.  Now lets look at this in how even a sinful world expects certain things for payment of a debt. (After all sin is actually a dept that has to be paid to God) Imagine that you owe a huge amount of money to the bank, and you go to the bank and say, "I know that I owe you a lot of money. However, I am totally broke, and cannot pay my debt with money. (but I have another plan to pay you.) Here's my plan: Every day, I will come and vacuum the carpet at this bank . Thus I will work for you until I pay off my debt. " How would the bank respond to your proposition? Perhaps the bank would get angry, or perhaps they would laugh at you, however, what is certain is that they would not accept your offering! Why would the bank not accept your offering?  Because there is no way you can pay your huge debt to the bank with some feeble "good works."