“I do set my bow in the cloud, and it shall be a token of a covenant…(Ge.9:13)”
One principle we need keep in mind is the principle of similitude. Realities of heaven are transposed to physical realities. The purpose of the Holy Spirit as the helper is to instruct man into all righteousness. What shall man understand of the Almighty Lord when shown with three personalities? Jesus Christ came to the earth to delineate the perfection of God. He is the image of the Invisible God. He fulfilled the Will of the Father and we can appreciate the Father-Son relationship since we are all began our lives as subject to our earthly parents. In submitting himself to redeem those who were in bondage he reconciled sinful man with God. His body was the means towards this. This Spirit of reconciliation works in similar fashion with principle of similitude.
Every natural object where the passage warrants shall hold a spiritual significance as well. Think of the parables of Jesus. Leaven has its shadow as the tares have. Before the foundation of the worlds began a body has been found which we understand is after the similitude of the body of Jesus. Heavenly reality is set down by the Spirit as a ‘body.’ Quoting the Psalmist the writer to the Hebrews speak thus: “A body hast thou prepared me (He.10:5,4,6-7)”. Such symbols are necessary so spiritual truths are to be spiritually understood. Secondly such symbols create a pattern holding up the entire narrative body from the Father and the Son alike, which is somewhat similar to our ancient bards resorting to rhyme patterns in poems where this facilitated memory. From the creation of Adam in the Garden of Eden to the New Jerusalem the body as a symbol ties great many scriptural passages creating coherence to the Core Will of God.
In the case of Noah, God is making a covenant with ‘you and every living creature that is with you, for perpetual generations’. Rainbow is the sky is a natural phenomenon and also doubles for a spiritual truth. As in the case of parables they are not merely an illustration observable in nature. It has a spiritual lesson built in. This is to be spiritually understood. In the case of parables many are Judgment parables as well. The Parable of the Unjust steward for instance. In the case of rainbow it also refers to Judgment of God. In the vision of John we are told that ‘there was a rainbow round about the throne…(Re.4:3).’
Judgement of God and grace are alike drawn from Mercy and it is what the covenant of God signifies. In the Noah episode we are shown rainbow as a token of God’s perfection.