Promises

And Noah builded an altar unto the LORD; and took of every clean beast, and of every clean fowl, and offered burnt offerings on the altar. And the LORD smelled a sweet savour; and the LORD said in his heart, I will not again curse the ground any more for man's sake; for the imagination of man's heart [is] evil from his youth; neither will I again smite any more every thing living, as I have done. While the earth remaineth, seedtime and harvest, and cold and heat, and summer and winter, and day and night shall not cease. I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth. And it shall come to pass, when I bring a cloud over the earth, that the bow shall be seen in the cloud: And I will remember my covenant, which [is] between me and you and every living creature of all flesh; and the waters shall no more become a flood to destroy all flesh.

God has made a promise that He will never destroy the world again. He made a promise to Noah and his sons that He will preserve the Earth and everything in it. Whenever there is a rainbow in the sky, we can take hope in the fact that God is looking at that very rainbow thinking about the promise He made to never destroy the world again with flood water. It's amazing that He would remember us. He could have just killed us all and started all over again without having to kill His only Son. But He remembered us.