Introduction

Paul writes that God "predestined us for adoption to himself as sons through Jesus Christ" (Ephesians 1:5). To understand what believers are predestined for, we need to understand what Paul meant by adoption. And that word meant something quite different in Paul's world than it does in ours.

Adoption in the Greco-Roman World

In our modern culture, we use the word adoption to indicate when a child who is not someone's biological offspring is legally made to be their son or daughter, most often at a young age. In contrast, Roman adoptio was neither designed nor intended to build emotionally satisfying families, support childrearing, or assist the fatherless. Rather, it was a legal process to direct and enforce changes in heirship and inheritance, particularly to transfer a father's authority and ensure succession in the male line.¹

Romans preferred small families of two or three children so as not to dilute their inheritance and social status. Adoption made sense for a man who had no children of his own, but if he already had heirs, adopting another risked splitting the estate. Because childhood mortality was high, adoptions often involved grown men instead of young children. It was a "safer investment," and the father could see what he was getting.² At the formal adoption, the adoptee gained his new father's name and the legal right to his estate.

Since formal adoption was practiced mainly for social, political, and financial reasons among the wealthier classes, most of the lower class had little need for the cumbersome legal process. If they wished to expand their family or help the fatherless, they practiced fostering instead.¹

The Roman world of the New Testament was shaped by adoption at the very top. Caesar Augustus, the emperor when Jesus was born (Luke 2:1), was originally named Octavian. He was the grandnephew of Julius Caesar, and at about eighteen he became Caesar's heir through a posthumous adoption written into Caesar's will.³ His successor Tiberius, the emperor during Jesus' ministry (Luke 3:1), was adopted by Augustus. And Nero, who was emperor when Paul wrote to the Romans, came to power because the emperor Claudius adopted him. When Paul wrote about adoption, his readers would have thought first of inheritance and legal standing.

Adoption in the Bible

When we read the passages in the Bible about adoption, we find them surrounded by language about inheritance, heirship, and legal standing. This is because of what adoption was in that culture: less about building a family and more about establishing an heir. The two are tied together, but this understanding of adoption as a legal proceeding of inheritance is vital to understanding what it means for us to be adopted into the family of God. Paul, a Roman citizen, would have been very familiar with these proceedings.

Romans 8: Waiting for Adoption

The first passage to highlight is Romans 8:23–25:

"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. For in this hope we were saved. Now hope that is seen is not hope. For who hopes for what he sees? But if we hope for what we do not see, we wait for it with patience."

Notice the phrase "we wait eagerly for adoption as sons." Paul is saying that believers are still waiting for their adoption, and that at our adoption we will receive the redemption of our bodies.

A few verses earlier, Paul says, "you have received the Spirit of adoption as sons, by whom we cry, 'Abba! Father!'" (Romans 8:15). The Spirit is the "firstfruits" of verse 23: the first part of a harvest that guarantees the rest is coming. We have received the promise of adoption, and through that promise we can rest and call God our Father, yet we are still waiting for its fulfillment.

Ephesians 1: An Inheritance Obtained and Guaranteed

In Ephesians 1, Paul uses similar language about our inheritance:

"In love he predestined us for adoption to himself as sons through Jesus Christ, according to the purpose of his will... In him we have obtained an inheritance, having been predestined according to the purpose of him who works all things according to the counsel of his will, so that we who were the first to hope in Christ might be to the praise of his glory. In him you also, when you heard the word of truth, the gospel of your salvation, and believed in him, were sealed with the promised Holy Spirit, who is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory." (Ephesians 1:4–5, 11–14)

In verse 11, Paul says that in Christ "we have obtained an inheritance," yet in verse 14 he says the Holy Spirit is "the guarantee of our inheritance until we acquire possession of it." So have we obtained an inheritance, or are we waiting for it?

Paul is not contradicting himself. He is describing a legal process. This is often explained as the "already but not yet" of salvation, but the adoption proceeding shows us exactly what that means here: we hold a present, legally secured claim to an inheritance that we will not take possession of until our glorification. In verse 13, Paul says that when we heard and believed, we "were sealed with the promised Holy Spirit." The adoption papers were written up and signed. On the day of resurrection, we will receive the inheritance promised and hoped for.

Galatians 4: Sons and Heirs

Galatians 4 uses the same legal picture. A child who is an heir is "no different from a slave" while he is under guardians, "until the date set by his father" (Galatians 4:1–2). God sent His Son "to redeem those who were under the law, so that we might receive adoption as sons," and so "you are no longer a slave, but a son, and if a son, then an heir through God" (4:5, 7). Here Paul speaks of adoption as already received, which fits the legal picture: our standing as sons and heirs is secure now, and the "date set by the father" for the inheritance is still ahead.

Children Now, Adopted at Glorification

Now, just because we are waiting for the fulfillment of our adoption and the receiving of our inheritance does not mean we are not children of God. Scripture is clear that we become children of God when we believe: "to all who did receive him, who believed in his name, he gave the right to become children of God" ( John 1:12). John holds both truths together: "Beloved, we are God's children now, and what we will be has not yet appeared; but we know that when he appears we shall be like him" (1 John 3:2).

Our adoption is simply not yet complete when we become children of God at justification. Our Western mindset finds it hard to separate these, but from a Greco-Roman point of view it would have been completely normal. When we are justified, we become children of God through His promise, and we receive the promise of an inheritance that we will receive at the formal adoption: our glorification.

We become children of God at justification. Our adoption is completed at glorification, when we receive our inheritance.

What We Inherit

The fulfillment of our adoption in the resurrection is the receiving of our inheritance, as promised and sealed by the Holy Spirit. Scripture describes that inheritance in several ways:

• The redemption of our bodies: "we wait eagerly for adoption as sons, the redemption of our bodies" (Romans 8:23).
• The kingdom: "Come, you who are blessed by my Father, inherit the kingdom prepared for you from the foundation of the world" (Matthew 25:34).
• The world: the promise to Abraham and his offspring was "that he would be heir of the world," and it came "through the righteousness of faith" (Romans 4:13).
• An imperishable inheritance: "imperishable, undefiled, and unfading, kept in heaven for you" (1 Peter 1:4).
• A reward: "from the Lord you will receive the inheritance as your reward. You are serving the Lord Christ" (Colossians 3:24).
• God Himself: "Behold, the dwelling place of God is with man. He will dwell with them, and they will be his people... He will wipe away every tear from their eyes" (Revelation 21:3–4).

In summary, our inheritance is life in the fullness of God's eternal kingdom: resurrection to a glorified body and eternal life, the riches of His glory and kingdom, and, above all, God Himself as our portion and joy.

Adoption and Predestination

This brings us back to Ephesians 1:5. God did not predestine particular unbelievers to be adopted when they are justified. He predestined those who believe to be adopted at their glorification. Adoption is a destiny God has fixed for everyone who is in Christ, and Paul tells us in the same passage how a person comes to be in Christ: "when you heard the word of truth, the gospel of your salvation, and believed in him" (Ephesians 1:13). This is why we read predestination as God's plan for those in Christ, not God planning who will be in Christ (see Predestination).

Adoption has also always belonged to God's people. Paul lists it first among Israel's privileges: "They are Israelites, and to them belong the adoption, the glory, the covenants" (Romans 9:4). God told Pharaoh, "Israel is my firstborn son" (Exodus 4:22). The Lord has been building His household from the beginning.

God's Plan of Adoption

God's plan of adoption was not Plan B for humanity. Even John Piper, a Calvinist, makes this point well:

We agree that adoption was planned from the beginning, though we understand that plan differently. Plan A was not a robotic humanity that never sinned or needed to be redeemed. Plan A was the creation of a humanity with free will, whom God knew would fall, together with a plan of redemption through Christ that leads to our adoption. Through this plan, the full range of God's glory, mercy, grace, and justice would be known by all.

Conclusion

Adoption in Scripture is not first about how we enter God's family; it is about what God has promised to those who are already His. We become His children when we believe, the Holy Spirit seals us as the guarantee of what is coming, and on the day of resurrection our adoption will be complete and our inheritance received. That is the destiny God set before the foundation of the world for everyone in Christ, and it is why we "wait for it with patience" (Romans 8:25).

1. Beryl Rawson, "The Roman Family," in The Family in Ancient Rome: New Perspectives (Croom Helm, 1986), 1–57.
2. Richard P. Saller, Patriarchy, Property, and Death in the Roman Family (Cambridge University Press, 1994).
3. "Adoption in the Roman World," Tabletalk (February 2020): https://tabletalkmagazine.com/posts/adoption-in-the-roman-world-2020-02/