The “Rain Bow” is God’s most devastating weapon ever used against the earth and it’s inhabitants. (The Hebrew word for “rainbow” actually means battle bow, a warrior’s weapon.) With it God was to do what He had never done before, and would never do again – destroy the earth and all life therein with a flood. God was provoked to pick up this mighty weapon of destruction in Genesis 6:5, where it says that “God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.” God grieved that He had made man, and decided to destroy him from the face of the earth. Along with man, God would destroy the beasts, every creeping thing, and the fowls of the air, for He repented that He had made them, also. “But Noah found grace in the eyes of God” (Gen. 6:8).
Therefore, God instructed Noah to build an ark of gopher wood, and God told Noah that He would establish His covenant with him. Then He told Noah to come into the ark, and to bring his family with him. God chose to save Noah from His coming wrath for this reason: “the Lord said unto Noah…for thee have I seen righteous before me in this generation” (Gen.7:1). He was also to bring with him into the ark seven pairs of every clean beast, male and female, one pair of every unclean beast, male and female, seven pairs of every kind of fowl, male and female, and one pair of every creeping thing, male and female. The gathering of these creatures wasn’t as difficult as it may seem, because the Lord caused the creatures to “come unto thee (Noah), to keep them alive” (Gen. 6:20).
Once Noah, his wife, his three sons and their wives, entered the ark, God’s fury was finally unleashed. He drew back his mighty bow, and poured down his vengeance upon the earth in “arrows of rain”. That this was surely a strange and terrifying phenomenon for the people of Noah’s day is attested to by these Bible passages: “the Lord God had not caused it to rain upon the earth” (Gen. 2:5) and “By faith Noah, being warned of God of things not seen as yet, moved with fear, prepared an ark… (Heb. 11:7). (Until that time, only a mist from the earth had watered the face of the earth.) This catastrophic flood came from forty days and forty nights of rain, and from the breaking up of the fountains of the great deep. This seems to indicate a pressurized release of the waters that may have been trapped below the ground when the waters were originally gathered together during the creation week, or sometime thereafter.
In 2nd Peter 2:5, Noah is called a preacher of righteousness. This implies that he most likely tried to warn the people around him of their danger and need to repent, but could also refer to a lifetime of preaching or being a good example to those around him. (Also, Noah would have taught his family about God because he was a righteous man.) As for the wicked humans left outside of the ark, the ridicule and scorn they must have heaped upon Noah and his family as they built the ark was rapidly turning into fear and panic as they began to realize that Noah was right after all – God was indeed punishing them for their sins and they were doomed to certain destruction. (That Noah was unable to convince anyone other than his family to come aboard the ark is not a reflection on his character or his message of hope, but simply more evidence as to how evil and unrepentant the people of Noah’s generation had become.) Some of them may have realized that Noah and his ark was their only hope and made one final desperate attempt to save themselves by rushing to the ark, crying out to be let in. But it was too late. Once the door to the ark was closed, it was not to be opened. And all who were outside the ark died in their sins.
The waters prevailed upon the earth so mightily for 150 days that even the highest hills and mountains were covered. Only Noah, his family, and the living creatures that were on the ark remained alive. “And God remembered Noah… and caused a mighty wind to pass over the earth, and the waters assuaged” (Gen. 8:1). About a year after the flood began, Noah and those with him were able to come out of the ark onto dry ground. Then God made his covenant with Noah. He promised Noah that He would never again cut off all flesh by the waters of a flood, and that He would never again send a flood to destroy the earth.
The token of this covenant would be between God and the earth, and with Noah and every living creature with him, for all generations to come. God, having picked up his bow once, now set it down in the cloud so that whenever He looked upon it, He would remember His everlasting covenant that “the waters should no more become a flood to destroy all flesh” (Gen. 9:15). To many Christians, the rainbow continues to be of huge symbolic significance because it shows that God will keep His promise to mankind as the bow always aims safely and peacefully away from earth and all who dwell upon it.