Before the flood people lived for hundreds of years. Due to the longevity of life, the earth’s population grew very rapidly. With the rapid population growth there was also a rapid growth of evil and sin in the world. Not only was the sin nature of man abounding, but also, demonic influence was rampant.
The sons of God and daughters of men (v. 2 & 4). Verse two of Genesis six has been difficult for many to interpret. There are many views as to who the sons of God were and what it exactly was taking place. This is a huge matter, because it is obvious that theses marriages between the sons of God and the daughters of men contributed to the moral decline in the world. Historically, three opinions have won a significant following for identifying the “sons of God”: (1) angels, (2) human judges or rulers, and (3) the descendants of Seth. Some believe in a mixture of these views and possibly in a mixture of all three of these views. The term ‘sons of God’ is used almost exclusively in the Old Testament in reference to angelic beings. There is also indication elsewhere in scripture that the ‘sons of God’ are, in fact, fallen angels. Look at 2 Peter 2:4-5. Also consider Jude 6. In both of these passages there is indication that there were fallen angels that committed a horrible crime worthy of them being chained in darkness waiting for their day of judgement. Going back to our text in Genesis 6, it seems unthinkable that fallen angels could themselves procreate. However, it is very possible that these fallen angels possessed certain evil men and impregnated the daughters of men and thus creating a race of super humans or giants as described in verse 4.
God will not always strive with man (v. 3). This, I believe, is a reference to the Holy Spirit who convicts man of sin and reveals to them their need for a Savior. God also gives man a period of 120 years before He would destroy the earth with a flood. Here we find both the wrath of God and the grace of God. The Bible is very clear that God is perfectly holy, righteous, and just. Sin must be dealt with. At the same time, God is gracious and slow to anger and full or mercy. He loves us and does not wish to see us die in our sins. Therefore, God gives grace. He gives man an opportunity to repent. In this case, He gives man 120 years to get things right. I firmly believe that there is appointed time in everyone’s life in which God will no longer deal with us. I believe that there comes a time after much conviction by the Holy Spirit that God will say enough is enough and will no longer draw us to salvation. In other words, the moment you first hear the Gospel, the countdown has begun. God is only going to give you so many opportunities to repent and believe on Him. How long will God strive with you? How long will He work to bring you to repentance? Only God knows. The bottom line is that it is a dangerous thing to play games with a holy and righteous God. When the Spirit of God gets a hold of you and convicts you, there must be a response before it is too late.
God grieves over what has become of man (v. 5-7). It is mentioned in verse six that the Lord ‘repented’ that he had made man. Most likely this does not mean that God changed His mind, rather, that He was sorry and grieved that He had made man due to way things have turned out. However, it certainly would not be wrong to suggest that God can change His mind. Some people have a problem with the thought that God can change His mind. They somehow think this cheapens the sovereignty of God. However, on the contrary, I believe it gives more credence to the sovereignty of God. Several times in scripture we see where God changes His mind. Our prayers can also affect the decisions that God makes. This, however, does not change the sovereign plan of God nor does it change His character. In this case, in verse 6, God is not really changing His mind or somehow wishes He never created man, rather, He is grieved over what has become of man. In verse 7, God decides to destroy man and all living things that He created. Here we see how sin breaks the heart of God. He would rather destroy the creation He loves so dearly Himself than to see it destroyed by sin. I do not think we fully realize the seriousness of sin. Even though verse 7 seems bleak and sad, yet, there is hidden in its horror, the grace of God. In God’s understanding of sin, it is such an horrific thing that it is better to destroy all that He loves than to see His creation suffer with the curse of sin. Think about it. How great is the love of God for us! I don’t think God was mad here. I don’t think He was having a fit of rage. Instead, God was grieving and His heart was broken. With a broken heart God decides to do the unthinkable as a last resort.
But Noah found Grace (v. 8). This one little verse in scripture is one of the most beautiful of all. Contrary to what we often think, it does not say that Noah was a good man. It does not say that Noah was righteous. Later we learn that Noah did walk with God like Enoch, but that does not mean that he was innocent. He deserved to be destroyed along with everyone else. But God saw a man who, though not perfect and perhaps very wicked himself, still believed. It is because of the faith of Noah that God gave Him grace. Praise God for His amazing grace! We who are lost in our sin. We who are totally and utterly depraved. We find grace at the foot of the cross!
 Mathews, K. A. (1996). Genesis 1-11:26 (Vol. 1A, p. 325). Nashville: Broadman & Holman Publishers.