By Genesis 6 the earth is filled with violence. “Then the LORD saw that the wickedness of man was great in the earth, and that every intent of the thoughts of his heart was only evil continually.” The LORD was sorry that He had made man, and it grieved Him in His heart. God's judgment is not cold or careless; it comes from a holy God who is grieved by sin.
Then come six beautiful words: “But Noah found grace in the eyes of the LORD.” Grace comes first. After that we read that Noah was a just man, perfect in his generations, and that “Noah walked with God.” Noah was not saved because he was better than everyone else; he found grace, and grace produced a righteous life.
God tells Noah to build an ark of gopherwood, three hundred cubits long, and to bring his family and the animals into it. Noah's response is simple: “Thus Noah did; according to all that God commanded him, so he did.” He worked for many years on something no one had ever seen, trusting God's warning of things not yet seen. Second Peter calls him “a preacher of righteousness.”
When Noah, his family and the animals had entered, “the LORD shut him in.” The rain fell forty days and forty nights, and the waters prevailed on the earth one hundred and fifty days. Then “God remembered Noah.” The waters receded, the ark rested on the mountains of Ararat, and the dove returned with a freshly plucked olive leaf. Noah's first act on dry ground was to build an altar to the LORD and worship.
In Genesis 9 God blesses Noah as He blessed Adam: “Be fruitful and multiply, and fill the earth.” He establishes His covenant never again to destroy the earth with a flood, and He gives a sign: “I set My rainbow in the cloud.” Yet the chapter ends honestly with Noah's drunkenness and Ham's dishonor. The flood washed the earth, but it could not wash the human heart. The world still needed the promised Seed.