Genesis 6 describes the revolt of the pre-flood world. After a period of silence in the historical record of the pre-flood world, Genesis 6 opens with a terrible picture of a demon infested planet. The sons of God had infiltrated human society. Who were the sons of God? It seems that they were demons. And just 120 years before the flood, the pre-flood world was certainly in an awful state.
In fact, man in the pre-flood world was in such a state of corruption that every intent of the thoughts of his heart was only evil continually (Genesis 6:5). There would only be 120 more years of mercy left for the men of the pre-flood world. The Lord was sorry that He made man on the earth and the blotting out of the pre-flood world was quickly approaching. Everything would be destroyed.
But Noah found favor in the eyes of the LORD. (Genesis 6:8) Noah lived a blameless life; he walked by faith. He was obedient to God. And so God spoke to Noah, reaffirming that the pre-flood world would indeed soon perish. God commanded Noah to build an ark. A massive ark. Just how big was it? It depends on whether the 18 inch cubit is used or whether a larger cubit is used, but regardless, the ark held everything that God commanded Noah to put in it. The ark held Noah, seven others in his immediate family, the animals of the earth, and an enormous supply of food.
Perhaps the most astounding part of Genesis 6 is that God says to Noah: But I will establish My covenant with you (Genesis 6:18). The mighty and all-powerful God would make a promise with fallen man. Thus while Genesis 6 is certainly a chapter which describes the violence and wickedness of man, it is also a chapter filled with grace. Even though it would have been perfectly just for God to blot out all men, not all men would perish in the flood. Through the means of an ark, grace would live on.
Outline of Genesis 6
Summary of Genesis 5
Summary of Genesis 4
Summary of Matthew 1