When God promised mercy to Noah, He gave a bow in the sky as a symbol of His covenant of grace. Notice, I said 'bow.' We commonly speak of the covenant symbol as a rainbow, but the actual symbol of God's grace is a brightly colored bow--a weapon of vengeance. Noah's culture had just endured the righteous display of God's wrath in a flood. To illustrate that His Divine wrath was assuaged, God gave to Noah and his family a bow in the sky. There are three things true of this bow:----
(1). The bow is pointed away from the earth, away from mankind.
(2). The bow has no string and thus cannot shoot any arrow of vengeance.
(3). The bow is unbent and as such serves as a true symbol of peace with God.
God gave the bow to Noah after the 'burnt offering' had been sacrificed on the altar, an act that gave the Lord 'a soothing aroma' (Genesis 8:20-21). Burnt offerings in the Old Covenant Scriptures prefigure the Messiah, the Lamb of God who would come to bear the wrath of God for His people and be well-pleasing (soothing) to the Father. Jesus Christ indeed came and fulfilled the Law, offering Himself once and for all for our sins (Hebrews 10:10-14).
Nature itself reveals the gospel. Next time you see a bow in the sky, tell your kids the story of Noah and the burnt offering that resulted in a promise of peace with God and the bow in the sky as a reminder of that peace. Impress on your hearers that because of the person and work of Jesus Christ, the bow of God's righteous wrath and vengeance is unstringed, unbent and unaimed toward we who have embraced His Son.