The sign of God’s covenant with Noah is a rainbow in the sky. God assures Noah that when he sees this it is a sign to all mankind that God will not ever send another global flood to destroy all life from the face of the earth.
Think about this for a moment. Noah and his family had never seen rain prior to the flood. If God had not made a point of assuring Noah that the rainbow was a sign that He would not flood the world again, it is entirely possible that Noah and his family would have been scurrying back to the ark every time a thunderstorm rolled in a dropped a passing shower. The rainbow that would be visible either as the rain approached or as it subsided, would be a regular reminder to Noah and his family that they need not fear another cataclysmic flood… ever!
I establish my covenant with you, that never again shall all flesh be cut off by the waters of the flood, and never again shall there be a flood to destroy the earth.”(v. 11)
This is the promise of God to Noah despite the fact that God knew the heart of humanity had not changed as a result of the flood. This is what is so amazing to me, God makes the statement in the latter part of 8:21 “for the intention of man’s heart is evil from his youth.” – God knew the flood had not cured the earth or mankind of evil, yet He promises not to wipe out mankind again in this fashion. It would seem He has a better plan in mind – one which the ark was a picture of. Thousands of years later God would send Jesus who would be a spiritual ark of safety for us that shields all those who choose to come on board from the destructive deluge of God’s coming judgment upon those who rebel against Him.
The cross has become the new symbol of that promise to those who believe – like a rainbow valentine communicating God’s love to his creation.