The rainbow is the sign that the Lord will preserve the present creation until the consummation of the covenant of grace when He will fully redeem His people from every tongue, tribe, and nation and bring them into the full enjoyment of a new creation. The sign of the Noahic covenant is therefore a gospel sign of the redeeming mercy of God in Christ (Isaiah 54:9–10).
Several years ago, my wife and I were driving back home from a trip out of town. At some point, we missed the exit sign on the highway leading to the town in which we lived. We drove for nearly thirty minutes before realizing that we were heading to the wrong city. We had completely missed the sign. Failing to see or to understand physical signs can result in unfavorable consequences; the same is true of failing to rightly understand God’s covenantal signs. This is evident today in the way many parade their sexual rebellion against God under the banner of a rainbow.
In redemptive history, the Lord established the covenant of grace with Adam, Noah, Abraham, Moses, David, and Christ. With each administration of the covenant of grace, God gave various divine signs. He set apart the rainbow in the sky to serve as the sign of the Noahic covenant. The Noahic covenant was God’s pledge that He would sustain the created order (Gen. 9:9–13). Because of His promise not to destroy the earth, mankind could be fruitful, multiply, and fill the earth (Gen. 9:1). In this sense, the Noahic covenant was a unique administration of the covenant of grace in that it contained a principle of common grace.
However, the Noahic covenant was ultimately serving the redemptive purposes of God. God was renewing the covenant promise He made to Adam when He inaugurated the covenant of grace (Gen. 3:15). In the Noahic covenant, God was setting the stage for the unfolding of redemptive history. Christ was in the lineage of Noah (Luke 3:23–38). Noah stood as a type of Christ, the head of a new creation (Gen. 8:13–19; 9:1–7). The ark itself served as a microcosm of redemptive history. The clean animals in the ark belonged to the Old Testament sacrificial system and typified the sacrifice of Jesus as the Lamb of God who takes away the sin of the world (Gen. 8:20; Ex. 12; John 1:29; 1 Peter 1:19). Clean and unclean animals together represented the Jews and gentiles, for whose salvation Christ came into the world (Acts 10:9–48; 11:18).