Today's passage, Genesis 8:20-9:17, brings us to God's covenant with Noah. It is at this point that we might think the problem is solved. If God wiped all of the evil people from the earth during the flood, then the issue has been resolved. However, this idea is crushed almost immediately in today's passage.
By looking at Genesis 8:21, we know that after the flood mankind is still sinful, God still hates sin and God still intends to bring glory to Himself through His creation. Genesis 8:21 says that the intentions of men are still evil. The incident between Noah and Ham in Genesis 9:20-25 will serve to remind us of this fact. We also remember from yesterday that Noah was not good of his own accord, it was the grace of God.
We know that even though God has shown Noah grace, He still hates sin. God will still judge, and punish, sin. If God hates sin and will judge, and punish sinners, why would He not destroy the entire world and give everyone what they truly deserve?
The simple answer is for the sake of His glory. God will not give up being glorified by His creation. He has created man in His image to put His glory on display. He will not fail. God gives Noah the sign of the rainbow to remind man, and Himself of the His promise. His glory cannot be displayed in His creation if he constantly destroys it for its sin. So what is the solution?
Sacrifice. Noah brings a sacrifice, a burnt offering, before God. The aroma pleased God, and He blessed Noah and his sons. This is the process of sin and atonement through sacrifice that we will see throughout the Old Testament. However, it is all pointing forward to one sacrifice that will be sufficient to cover all sin. Romans 5:18-21