Part 4: Quick Survey of Adoption's Marking Function (read the other parts here)
As I noted in part 3, God’s work of adoption has a “marking” function in the grand story of redemption. It plays a leading role from before the beginning of the unfolding story of redemption (before God created the world) all the way to the end (when all of God’s adopted children enjoy the full privileges of their adoption on the new earth in glorified bodies). Here is a brief overview of adoption's marking function in the grand story of redemption:
Act One: In Ephesians 1:4-5, Paul states that in love God the Father "predestined us for adoption as sons through Jesus Christ, according to the purpose of his will." This is really quite amazing: adoption's marking function began before God created the universe. Even before the earth existed God marked us out (i.e., predestined us) for the great privilege of being His children through adoption. Adoption was not a divine afterthought. It was in God's mind even before the dawning of human history. One amazing truth we learn from Paul's words here, as John Piper has said, is that "adoption is greater than the universe."
Act Two: Given Israel's central role in the unfolding story of God's work of redemption, adoption's importance within the history of salvation can be inferred from Romans 9:4 where Paul identifies adoption as one of the great privileges that Israel enjoyed as God's chosen people. He writes, "They are Israelites, and to them belong the adoption, the glory, the covenants, the giving of the law, the worship, and the promises." Scholars believe that Israel received adoption, becoming God's corporate son, when God constituted them a nation at Mt. Sinai, three months after He delivered His people from Egypt . It is very significant that adoption shows up at this key moment within the unfolding story of redemption.
Act Three: In Galatians 4:4-5, referring to the wonderful climax of redemptive-history, Paul writes, "When the fullness of time had come, God sent forth his Son, born of woman, born under the law, to redeem those who were under the law, so that we might receive adoption as sons" (emphasis mine). Paul identifies adoption as the purpose or objective of redemption. He could not have written it any more clearly. God sent His Son to redeem us so that we might be adopted! God the Father sent His eternal and natural Son so that we could become His adopted sons. Once again, adoption shows up at a key time—the climactic time—within the unfolding story of redemption.
Act Four: As I have mentioned a couple times already, adoption plays a leading role from before the beginning of the story of redemption (Ephesians 1:4-5) all the way to the consummation of redemption's story when all of God's adopted children enjoy the full privileges of their adoption on the new earth. In Romans 8:23, Paul writes, "And not only the creation, but we ourselves, who have the firstfruits of the Spirit, groan inwardly as we wait eagerly for adoption as sons, the redemption of our bodies" (emphasis mine). Paul identifies the redemption or glorification of our bodies as the consummation of our adoption. God, as it were, finalizes our adoption as sons when the story of redemption reaches its intended goal.
While the word adoption is only used five times in Scripture, its importance is established by the leading role it plays within the story of God's gracious work of redemption. As we grow in our understanding of adoption's leading role within the grand story of redemption, we will find ourselves thinking vertically about adoption (i.e., God adopting us) before we think horizontally (i.e., couples adopting children). As a result, our experience of horizontal adoption will be greatly enriched.