Why did God flood the earth?

from the old testament

• The reason for the flood is given in Genesis 6:5–7: "The LORD saw that the wickedness of man was great in the earth, and that every intention of the thoughts of his heart was only evil continually. And the LORD regretted that he had made man on the earth, and it grieved him to his heart. So the LORD said, 'I will blot out man whom I have created from the face of the land, man and animals and creeping things and birds of the heavens, for I am sorry that I have made them.'" The passage uses anthropomorphic language. It does not mean that God was met with unforeseen circumstances that caused Him to think He had made a mistake by creating mankind; rather, it expresses God's deep sadness over the wickedness of mankind.
• The purpose of the flood was to wipe out the wickedness that infiltrated the world—which included widespread violence, according to Genesis 6:11—by wiping out the wicked people, which was everybody except Noah and his family. Later on, we find that even Noah and his family rebelled (Genesis 9:20–24), for even the best of us are still sinners.

from the new testament

• The New Testament teaches that God flooded the earth because of widespread human wickedness and corruption, demonstrating His judgment against sin while also providing a way of salvation. In 2 Peter 2:5, Noah is described as "a preacher of righteousness" (NIV), who warned of the coming judgment through the flood.
• The flood is seen as a clear example of God's justice in punishing a sinful world Hebrews 11:7 highlights Noah's faith in responding to God's warning.
• Additionally, 1 Peter 3:20–21 connects the flood to baptism, symbolizing salvation and God’s mercy in preserving Noah and his family. Thus, the flood reveals both God’s holiness in judging sin and His grace in offering deliverance to those who trust Him.

implications for today

People today are still wicked, but God promised that He would never again destroy the world by a flood, and He gave the rainbow in the sky as a reminder of His promise (Genesis 9:8–16). This promise does not mean that God overlooks sin. One day, He will destroy the earth by fire. Peter explains, "The heavens existed long ago, and the earth was formed out of water and through water by the word of God, and that by means of these the world that then existed was deluged with water and perished. But by the same word the heavens and earth that now exist are stored up for fire, being kept until the day of judgment and destruction of the ungodly" (2 Peter 3:5–7). And he adds that "the day of the Lord will come like a thief, and then the heavens will pass away with a roar, and the heavenly bodies will be burned up and dissolved" (2 Peter 3:10).

Peter tells us what this final judgment means for us: "Since all these things are thus to be dissolved, what sort of people ought you to be in lives of holiness and godliness, waiting for and hastening the coming of the day of God, because of which the heavens will be set on fire and dissolved, and the heavenly bodies will melt as they burn! But according to his promise we are waiting for new heavens and a new earth in which righteousness dwells" (2 Peter 3:11–13).

After the destruction of the flood, the world was not made perfect, and mankind continued in rebellion. After the destruction by fire, the new heavens and new earth will be created, and the world will be characterized by righteousness. The only ones who escaped the flood were those who got on board the ark. Likewise, the only ones who will escape the coming judgment are those who take refuge in Christ.