"And he gave unto them commandments, that they should worship the Lord their God, and should offer the firstlings of their flocks, for an offering unto the Lord. And Adam was obedient unto the commandments of the Lord.
And Cain loved Satan more than God. And Satan command him, saying: Make an offering unto the Lord.
And in the process of time it came to pass that Cain brought of the fruit of the ground and offering unto the Lord.
But unto Cain, and to his offering, he had not respect. Now Satan knew this, and it pleased him. And Cain was very wroth, and his countenance fell.
I was wondering why the fruit of the ground wasn't an acceptable offering to the Lord. If your a farmer and that is all you raise wouldn't that be acceptable? Then I went back and read what had been asked of them. In verse five no where does it mention vegetables. The more I thought on it, and the offering being in a similitude of the sacrifice of the Savior, there was a need for blood to be spilled. Vegetables don't have blood, just like Satan doesn't either. What a mockery Satan was making of the Savior's atonement and sacrifice to inspire Cain to offer up vegetables. The sacrifice of an animal was not an impossibility for Cain because he was a farmer, he could have traded his vegetables for the needed animal. He just didn't want to. He had no desire to please God. Satan knew that the sacrifice of a vegetable was a reference to the Father who Cain was really worshiping. The one who had no blood, not His only Begotten Son. That is why Satan inspired Cain to do that very thing.