"I have set my rainbow in the clouds, and it will be the sign of the covenant between me and the earth." (Genesis 9:13)
After the flood, God establishes the first formal covenant in Scripture, the Noahic covenant, with Noah and his sons and every living creature. It is unconditional and universal: God will never again destroy all life with a flood. He gives the sign of this covenant: I have set my rainbow in the clouds, and it will be the sign of the covenant between me and the earth. The rainbow is not merely a beautiful meteorological phenomenon. It is a divine promise, written in light across the sky, renewing creation after judgment. The Catechism calls the Noahic covenant the first stage in the progressive revelation of God's plan of salvation, the establishment of the cosmic framework within which all subsequent covenants will be made (CCC 56).
God also gives new regulations for this new beginning: the fear and dread of humanity will be on every animal, but every moving thing that lives will be food. However, the life of the creature, which is its blood, must not be eaten. And most significantly: whoever sheds human blood, by humans shall their blood be shed, for in the image of God has God made mankind. The prohibition on murder is grounded not in social utility but in theology: to kill a human being is to attack the image of God. This is the foundation of every subsequent account of human dignity in the biblical tradition.
Brothers and sisters, every rainbow you see is a divine promise. Not a cliche, not a greeting card. The covenant God made with Noah after the flood, renewed in the sky every time light meets rain. The God who makes and keeps covenants is the same God who keeps every promise he has made to you. When you see the rainbow, remember: he will not abandon what he has made. He remembers his covenant. Forever.
Lord God, you set your rainbow in the clouds as the sign of your covenant with all living things. You bound yourself by promise never to abandon your creation. Help us to trust your covenant word with the same certainty that the rainbow declares it. Through Christ our Lord. Amen.