From Scripture. This answer is plainly backed by the text of Scripture.
The question goes like this: God made the universe, people, and all the animals, and He said it was all good. But later it all turned bad, and He destroyed them in a flood. So did God make a mistake? Did He second-guess Himself?
On the sixth day of creation, God said what He made was “very good”. Soon after, Adam and Eve were sent out of the garden. It had all been good just a week before. But even after Adam disobeyed, not everything was bad. There was Noah (Genesis 6:9).
When God saw much of His creation turn to evil and corrupt itself in many ways, He repented, which means He changed His mind, about making them (Genesis 6:6). Many people say, “I thought God does not change His mind.” He does not, unless He already said He would. If He did not change His mind after saying He would, that would be changing His mind anyway. That can be a little confusing.
Here is what Scripture says. In Jeremiah 18:8-9, the Most High speaks through the prophet Jeremiah. He says that if a nation He promised to bless turns and does evil, He will change His mind about the good He planned for them. The other way around is true too. That is exactly what He did to everyone destroyed in the flood. That is why Genesis 6 says, “And it repented the LORD that he had made man on the earth”.
Many parables in the Word explain God’s plan using farming, and that is how we should see this too. Adam was like a seed that was planted, a plant made from the dust. Think of the flood as getting rid of the parts of the plant you cannot eat, while harvesting and replanting the part God wanted, which was Noah. The second destruction of the world (the first was the flood) is often described as a harvest. In it, the good are separated from the evil. The good are often compared to the parts of a plant you can eat. For example, Matthew 3:12 compares the wheat that is gathered to God’s saints. The evil, meaning sinners who will not repent, are compared to the chaff, the parts you cannot eat, which is burned in the fire.
God did not cut corners or skip to the end. In all His wisdom, He planted a seed that grew and made many other seeds. He cleaned and filtered all through history until the True Seed, His Son, was planted (John 12:24). By His grace, some of us are seeds that will grow good fruit, and others will not. In the end, God will separate the two (Matthew 13:37-43).
So what God said in Genesis was true, because “we know that all things work together for good to them that love God, to them who are the called according to his purpose” (Romans 8:28). Very good.
Answered by Taught of Yah
