Adopted Into Grace: Roman Law, the Gospel, and the Fatherhood of God
Adoption is not just an aspect of the Gospel. It is the Gospel.
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by Rod D. Martin
March 30, 2025
When Paul describes our salvation, he invokes the law — specifically, the Roman law concerning adoption. He does so deliberately, decisively, and repeatedly. His hearers understood what he was saying: they lived under that law. There can be no question regarding his intent.
And that has enormous implications for the Gospel, and our status before God.
In Roman law, adoption was no soft sentiment. It was a public legal act that completely redefined who a person was: his rights, his duties, even his debts. Paul wasn’t waxing poetic when he said we’ve received “the Spirit of adoption”.1 He was invoking the most powerful legal metaphor available in the Greco-Roman world, a metaphor — and a reality — that explained not just what God has done, but who we become as a result.
He was also explaining what kind of Father God is.
What Roman Adoption Meant
In Roman civil law, adoption was only rarely the domain of parents seeking infants. It was primarily a tool of inheritance, as in the case of Julius Caesar’s adult adoption of his nephew Octavian. Adoption was usually a strategic legal transaction between intentional, consenting adults, used to secure heirs (political as much as financial), transfer wealth, and perpetuate family lines.
Roman adoption came with three enormous implications, enshrined in law:
1. Irrevocability: A natural son could be disowned. An adopted son could not. Adoption created a new legal status that could not be undone.
2. Erasure of past debts and obligations: Adoption wiped the slate clean. If the adoptee had debts, they vanished. His old family ties were legally dissolved. He became a new person in the eyes of the law.
3. Full rights of inheritance: The adopted child wasn’t “like” a son. He was a son, in every legal sense. He received the full status, name, and inheritance of his new family.
Paul’s Roman readers would not have missed the implications. To say that God has adopted us is to say that we are no longer legally bound to our old identity — our sin, our shame, our condemnation. It is all gone. Nullified. Buried. We have a new name, a new inheritance, and a new status that can never be revoked.
This is not just an aspect of the Gospel. It is the Gospel, expressed in legal form: God has made us His children — not figuratively, but legally, relationally, irrevocably.
When Jesus tells Nicodemus he “must be born again”,2 this is precisely what He means.
From Slaves to Sons
Paul’s recurring contrast between slavery and sonship only makes sense in this legal context. A slave in Roman society was property. A son was an heir. Paul tells us, “you did not receive the spirit of slavery to fall back into fear, but you have received the Spirit of adoption as sons”.3 This is not spiritual allegory. It is a courtroom declaration.
In Christ, we are no longer outsiders looking in. We are not merely sinners with a second chance. We are no longer children of the flesh, or of the devil. We are heirs, co-heirs with Christ4 the only begotten (or natural) Son,5 the firstborn of many (adopted) brothers.6
The force of Paul’s claim intensifies in Galatians: “So you are no longer a slave, but a son, and if a son, then an heir through God”.7 That “if” is not figurative or speculative — it is legal. It is Paul’s shorthand for the full status of adoption under Roman law. He is saying: God didn’t just release you from bondage; He gave you the title deed to the house. You were not just freed — you were claimed.
Modern readers may find this idea of inheritance confusing: Is God going to die? No. But in an era of emperors and nobles such as Paul’s, an heir had a special place and status both before his father and the world, even while his father still lived. That is our status before God, or rather, the status of all who are redeemed.
Scottish law professor Francis Lyall drives this home.8 Roman adoption was not simply a change of relationship. It was a change of jurisdiction. A new father meant new law, new debts (none), new obligations (glory), and new destiny (inheritance).
The adoptee didn’t bring his baggage. He couldn’t. It had been erased as a matter of law. The magnitude of that — imagine having your mortgage completely cancelled — is why a Roman adoption had to be granted by a court. Likewise, our adoption is granted by the Judge of the whole world.
Debt Forgiven, Identity Rewritten
This is why the Gospel cannot be reduced to forgiveness alone. Forgiveness cancels punishment. Adoption confers identity. Forgiveness means you’re no longer guilty. Adoption means you now belong.
This is why Paul’s presentation of the Gospel is both legal and relational. Indeed “there is now no condemnation for those who are in Christ Jesus”.9 This is the doctrine of justification. But it’s not the final word. The Spirit Himself bears witness that we are children of God. And “if children, then heirs — heirs of God and fellow heirs with Christ”.10
No condemnation, because your debts are gone. No distance, because you’ve been brought near. No uncertainty, because your inheritance is fixed. The law once testified against us. But now, through adoption, the law testifies for us. We have been legally transferred from the domain of darkness into the household of our new Father.
And in Roman law, as Lyall notes, such a legal transfer wasn’t private or provisional. It was public, binding, and irrevocable. This is the doctrine of the perseverence of the saints, what Baptists usually call the security of the believer. You cannot lose your adoption, assuming you were in fact adopted, because adoption is forever.
Many fear losing their salvation. This is an impossibility. But many think they’re saved because they recited a prayer, or walked an aisle. Scripture, however, is quite clear: “if you confess with your mouth that Jesus is Lord and believe in your heart that God raised Him from the dead, you shall be saved.”11 Many who profess the Name do not truly believe. But for those who genuinely do, “He has given the right to become children of God”,12 and “no one may snatch us from His hand”.13
The Father’s Heart Behind the Law
All of this legal precision serves one relational end: sonship. Not servitude. Not probation. Not parole.
In Roman adoption, the adoptee didn’t earn his place. He was chosen. And in the case of God’s family, chosen not because of worthiness, but because of divine love. “In love He predestined us for adoption to Himself as sons through Jesus Christ”.14 That’s the motivation. Love, not merit. Election, not works.
Such great love — of the Father for us, and of ourselves for the Father and for our Savior — will surely produce good works.15 How could it not? If I love someone I want to please them. But those works are not the basis of our salvation.16
And here the legal metaphor gives way to something even deeper. Paul tells us that the Spirit we have received cries out, “Abba! Father!” “Abba” is not formal: its best English equivalent is “Daddy”. This is not transactional. It’s relational. It’s not legalese. It’s the joyful cry of a child running to a daddy whom he knows is his.
Paul’s use of “Abba” is no sentimental flourish. It’s a theological earthquake. Jesus used that word in the Garden of Gethsemane. Now Paul says we say it also. The access that belonged to the Son by nature now belongs to us through our adoption.
This is what the Gospel is — not just pardon, not just escape, not even just rescue. It is that the Judge has found us “not guilty” by reason of Christ’s substitutionary sacrifice, and has willingly and gladly become our Father.
And He will never disown His children.
The Healing Doctrine Our Age Has Forgotten
Our culture is drowning in fatherlessness: broken homes, fractured families, and absent dads. And the problem is not just one-way: there is a rising trend of children deserting their parents, orphans by choice not need, with 26% of Millennials deliberately estranged from their fathers.
It is no coincidence that so many people today struggle to understand the Gospel. The very framework God has given us — Fatherhood, sonship, adoption — has been shattered in our modern generational memory.
And yet, this is the very truth that speaks hope to our orphaned generation.
God is not merely a sovereign. He is not merely a lawgiver. He is not a cosmic CEO or distant deity. He is a Father. And not in name only, but in reality: He loves, provides, protects, disciplines, delights, and never lets go. He has bound Himself to us in the most permanent legal terms imaginable, and sealed it with the blood of His Son.
This is not metaphor. This is identity. This is the Gospel.
Not Just a Theological Detail — The Theological Core
The doctrine of adoption is not a minor chord in Paul’s symphony. It is the key in which the whole piece is written. It is how God accomplishes our salvation, and how He frames our new life.
It demands a response. The foundational reality of our status before God is that — inexplicably — He loved us so much He made us His children. Everything else flows from that.
Theologians and pastors often rightly focus on justification by faith. But justification answers the question of guilt: it’s just the entry point. Adoption answers the question of belonging. And without the latter, the former feels incomplete. God didn’t just save us from something. He saved us for something and to something. He made us a family.
This is why our theology must be driven not just by clarity, but by love. Not just by law, but by the Lawgiver who, through adoption, becomes Abba. The more we understand that, the more everything else falls into place. The law becomes instruction, not condemnation. Discipline becomes proof of love, not rejection. Obedience becomes joy, not obligation.
If you study your Earthly dad (let's call it "dadtrine" or "dadology") you certainly do so to some degree to stay out of trouble, and to some degree because it makes life easier. But mostly, you do it because you love him. And loving him, you want to please him.
That’s part and parcel of the doctrine of sanctification. And it’s beautiful.
Conclusion: The Gospel in Legal Form, the Gospel in a Father’s Voice
Roman adoption law gave Paul the tools to articulate the full glory of the Gospel. And it gives us a framework to understand who we are.
We are not just redeemed. We are not just forgiven. We are not just justified.
We are adopted. We have a Father. We have a new status. We have an eternal home.
The Judge has ruled. Our debts are gone. Our status is changed. And our Father opens His arms, not to strangers, but to daughters and sons.
See Also:
Recent Articles:
Romans 8:15
John 3:1-21
Romans 8:15
Romans 8:17
John 3:16
Romans 8:29
Galatians 4:7
Lyall, Francis. Slaves, Citizens, Sons: Legal Metaphors in the Epistles. Academie Books, 1984. This is by far the foremost treatise on the topic. My esteemed acquaintance Professor Lyall, the Emeritus Chair of Public Law at the University of Aberdeen, is also widely known for his Space Law: A Treatise, recently released in its Third Edition. He may be one of the coolest people alive.
Romans 8:1
Romans 8:16–17
Romans 10:9-10
John 1:12
John 1:28, Romans 8:31-39
Ephesians 1:4-5
James 2:14-26
Romans 6:23, Ephesians 2:8-10
What a magnificent essay - so reassuring and moving. Thank you.
A good Sunday morning read. Thank you.