This is the second installment in a series exploring St. Paul’s Letter to the Romans with the help of St. Thomas Aquinas.
Paul has introduced himself as a servant of Jesus Christ, called to be an apostle and set apart for the Gospel of God. He now begins to unfold the grandeur of the Gospel entrusted to him:
which he had promised beforehand, through his Prophets, in the Holy Scriptures, about his Son, who was made for him from the offspring of David according to the flesh, — Romans 1:2-3
These words answer two fundamental questions.
First, where does the Gospel come from? It comes from God, who promised it beforehand through the prophets.
Second, what is the Gospel about? At its heart, the Gospel concerns God’s Son, eternally begotten of the Father and truly made man from the line of David.
The Christian faith is therefore neither a late religious invention nor a collection of abstract moral principles. It is the fulfillment of God’s ancient promises in the Person of Jesus Christ.
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1. The Gospel did not appear without preparation
The Christian proclamation entered publicly into history at a particular time. Jesus was born under the Roman Empire; he preached in the land of Israel; he suffered under Pontius Pilate; and his apostles carried his Gospel throughout the nations.
Because the preaching of Christianity began at a definite historical moment, pagans could dismiss it as a recent novelty. Aquinas sees Paul’s words as an answer to this objection.
The Gospel may have begun to be preached openly at a particular time, but it had been promised long beforehand. The coming of Christ was prepared through the history of Israel, foretold by the prophets, and preserved in the sacred writings.
The Old Testament is therefore not an unrelated religious document that Christians happen to keep. It is the divinely ordered preparation for Christ. The promises made to Abraham, the kingship of David, the sacrificial worship of Israel, and the words of the prophets all point forward to their fulfillment in him.
Christ does not enter history as a divine afterthought. His coming unfolds the eternal plan of God.
As St. Paul would later teach, the Gospel fulfills what God had promised to the fathers (Acts 13:32–33). Christianity is new because something truly new has happened: the Son of God has become man. Yet it is also ancient because this saving event fulfills the promises planted throughout the history of Israel.
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2. The reliability of the promise
Aquinas next draws attention to Paul’s use of the language of promise.
A prediction may express only what someone thinks will happen. A divine promise rests upon the faithfulness of the one who makes it. God neither deceives nor is deceived. What he promises, he has the wisdom and power to accomplish.
The Gospel is therefore reliable because God is reliable.
Christian hope does not rest upon optimism, emotion, or the assumption that history will naturally improve. It rests upon the fidelity of God. The same God who made the promises has acted to fulfill them in Christ.
This does not mean that the prophets always understood the full depth of everything entrusted to them. The mystery exceeded the comprehension of any one human author. Nevertheless, the Holy Spirit directed their testimony toward the saving work that would reach its fullness in Jesus.
The Gospel is not a human attempt to climb toward God. It announces what God has promised and what God himself has accomplished.
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3. God spoke through his prophets
Paul says that God made these promises through his prophets.
Aquinas emphasizes the possessive word. Not everyone who claims prophetic insight speaks for God. Some speak from their own imagination; others may even be influenced by forces opposed to God. God’s prophets, by contrast, receive their mission and message through the divine Spirit.
Their authority does not come merely from intelligence, eloquence, or political influence. They are witnesses because God has called and inspired them.
This also helps us understand biblical prophecy correctly. A prophet is not principally a religious fortune-teller. The prophet speaks God’s word into history. He calls God’s people to repentance, interprets events in the light of the covenant, and announces the divine promises.
The prophets differ in personality, historical circumstances, and literary style. Yet through this genuine human diversity, God prepares one coherent history of salvation.
Isaiah speaks of the servant who suffers. Jeremiah announces a new covenant. Ezekiel looks toward purification, a new heart, and a new spirit. Micah associates the ruler of Israel with Bethlehem. The Psalms speak of the Lord’s Anointed, the rejected stone, and the king whose dominion will extend over the nations.
These strands meet in Christ—not because the Church has arbitrarily forced them together, but because the same God who inspired the promises brought about their fulfillment.
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4. Why the promises were written
God’s promises were not merely spoken and then left to the uncertainties of human memory. They were committed to writing.
Aquinas sees this as a further mark of the Gospel’s dignity. Important truths intended for future generations are written so that they may be preserved, examined, and handed down. By speaking of the Scriptures, Paul presents the Gospel as the fulfillment of a public and enduring testimony.
The written character of prophecy also enables the faithful to compare promise and fulfillment. The apostles did not simply claim that Jesus was the Messiah and then invent a past to support that claim. They proclaimed that the God who had spoken in Israel’s Scriptures had now fulfilled his word in Jesus Christ.
The written promises form part of the continuity of salvation history. The God of the Gospel is the God who spoke through Moses and the prophets. Aquinas observes that Paul’s words exclude the error of those who attempted to separate the Father of Jesus Christ from the God of the Old Testament [Commentary on Romans (St. Thomas Aquinas) §1:40–41].
There are not two rival gods—one associated with creation and Israel, and another with Christ and redemption. There is one God, one divine plan, and one history of salvation.
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5. Why these Scriptures are called holy
Paul does not refer merely to ancient writings. He calls them the holy Scriptures.
Aquinas gives three reasons for this holiness.
First, the Scriptures are holy because of their source. Their human authors spoke under the inspiration of the Holy Spirit (2 Peter 1:21; 2 Timothy 3:16).
Second, they are holy because of their content. They communicate the things of God and reveal his saving works.
Third, they are holy because of their effect. God uses his word to draw human beings away from sin, consecrate them in truth, and lead them toward holiness.
Sacred Scripture is thus not merely an ancient object of scholarly analysis. Historical and literary study are valuable, but the purpose of Scripture extends beyond information. God addresses his people through these writings and forms them for communion with himself.
The Scriptures are holy because they come from God, speak of God’s saving mysteries, and lead us toward God.
The Old Testament must therefore never be treated with contempt. It is not an embarrassing remnant of a primitive religion. Paul calls these writings holy, and he presents their promises as God’s own preparation for the Gospel [Commentary on Romans (St. Thomas Aquinas) §1:40–41].
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6. The Gospel is about a Person
After commending the Gospel through its divine origin, antiquity, reliability, prophetic witnesses, and preservation in Scripture, Paul turns to its content.
The Gospel concerns God’s Son.
This is essential. Christianity is not founded primarily upon an ethical system, a philosophical theory, or a political program. It certainly contains moral teaching, illuminates philosophical truth, and has consequences for social life. Yet its center is a Person.
The Gospel is Jesus Christ.
Everything depends upon who he is. If Jesus were merely an unusually holy man, Christianity would become one religious movement among many. If he were merely a messenger, our attention would ultimately move beyond him to the message he delivered.
But Jesus does not merely bring the Gospel as something separate from himself. He is the incarnate Son of God, and the saving events of his life, death, and Resurrection constitute the heart of the Gospel.
The eternal Son is the Word and Wisdom of the Father. Through him all things were created, and in him the meaning of creation and history is revealed. The one whom the prophets anticipated is not simply another prophet. He is the Son to whom the prophets bear witness.
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7. The eternal Son of the Father
Aquinas carefully distinguishes Christ’s eternal origin from his temporal origin.
According to his divine nature, the Son is eternally begotten of the Father. He did not begin to exist at Bethlehem. Before his human birth, before David, before Abraham, and before creation itself, the Son eternally is.
This sonship cannot be reduced to adoption. Christians become adopted children of God through grace, but Christ is the Son by nature. He does not rise from being a mere man to divine status as a reward for exceptional virtue. Rather, the eternal Son descends in mercy and assumes our humanity.
Nor is the Son merely another name for the Father. The Father and the Son are distinct divine Persons. The Father sends the Son, and the Son lovingly accomplishes the will of the Father. Personal distinction does not divide the divine nature, for the Father and the Son are one God.
Finally, the Son is not the highest of God’s creatures. All created things were made through him. The one through whom everything was created cannot himself belong to the order of created things [Commentary on Romans (St. Thomas Aquinas) §1:33–34].
Aquinas summarizes the true faith by explaining that Christ is the Son by origin rather than adoption, in truth rather than in name alone, and by eternal generation rather than creation [Commentary on Romans (St. Thomas Aquinas) §1:33–34].
The Son is distinct from the Father as a Person, yet one with the Father in the divine nature.
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8. The Son who truly became man
Paul proceeds from Christ’s eternal origin to his temporal birth from the line of David.
The language Aquinas receives from the Latin tradition speaks of the Son as being “made” from the seed of David according to the flesh. This must be interpreted carefully.
It does not mean that the Son was created. Nor does it mean that a man from David’s line eventually became the Son of God. The subject of the whole statement is the eternal Son. It is the Son who assumed human nature and entered David’s family line.
The Son did not begin to be God. He began to be man.
Aquinas therefore explains that it is correct to say that the Son of God was made man, because the eternal Son was not always man. But it would be misleading to say that a mere man became the Son of God, as though Jesus had first existed as an ordinary human person and afterward acquired divine status [Commentary on Romans (St. Thomas Aquinas) §1:36–37].
The movement is not from humanity upward to divinity. It is from divine glory downward into the humility of our human condition.
The Incarnation is an act of divine condescension: the eternal Son truly assumes what he did not previously possess—a complete human nature—without ceasing to be what he eternally is.
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9. One Person, not two
Aquinas next defends the unity of Christ’s Person.
The Son of God did not merely dwell in the man Jesus as God dwells by grace in the saints. God certainly inhabits the souls of the just, but the Incarnation is a unique and immeasurably deeper mystery.
In Christ, the divine and human natures are personally united in the eternal Word.
There are not two persons standing beside one another: one divine and one human. The Son of God and the Son of Mary are not separate subjects cooperating closely. The child born of Mary is the eternal Son himself living a truly human life.
This is why the Church can confess that God was born of Mary, that God suffered in the flesh, and that the crucified man is the Lord of glory. The divine nature itself is neither born nor capable of suffering. Yet the Person who is born and suffers according to his humanity is truly God the Son.
The Incarnation is not merely the presence of God within a holy man. It is the personal union of the Word with a complete human nature.
The one who was eternally begotten of the Father is the same one who was born in time of the Virgin Mary.
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10. Two natures without change or confusion
Christ is one divine Person in two natures: divine and human.
The Word did not change into flesh as one material thing might be transformed into another. God is immutable. If the divine nature could cease to be divine or be converted into something created, God would not truly be God.
Aquinas therefore explains that the Son’s becoming man must not be understood as a change within God. It is a new personal union brought about through a change in the creature: a human nature begins to exist in personal union with the eternal Word [Commentary on Romans (St. Thomas Aquinas) §1:36–37].
The Son remains fully divine while becoming fully human.
His humanity is not imaginary. Nor is it incomplete. Christ possesses a true human body and a true human soul. He thinks with a human intellect, loves with a human will, experiences human suffering, and undergoes real human death.
Yet these human experiences belong to one divine Person: the eternal Son.
The Incarnation neither divides Christ into two persons nor mixes his two natures into a third kind of being. His divinity remains truly divine, and his humanity remains truly human. They are united without confusion in the one Person of the Son.
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11. Why Paul says “according to the flesh”
Paul says that the Son came from the seed of David according to the flesh.
This expression does not mean that Christ possessed only a body without a human soul. In biblical usage, flesh can refer to the whole human being considered in the weakness and mortality of the present condition.
Paul’s meaning is that, according to his human nature, Christ truly belongs to David’s line. According to his divine nature, however, the Son is eternally begotten of the Father.
This distinction protects both sides of the mystery:
Jesus is truly God, not an adopted son or exalted creature.
Jesus is truly man, not a divine appearance wearing an imaginary body.
The eternal Son entered a real human genealogy. He received flesh from the Virgin Mary and belonged historically to the house of David.
The Incarnation is not mythology. It takes place within human history, family descent, political rule, and the bodily life of a particular woman.
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12. Born and “made” of a woman
Aquinas considers why Scripture can describe Christ both as born of a woman and as made of a woman.
Christ was truly born because he received his human nature from Mary, was conceived in her womb, and passed through the ordinary period of human gestation. His birth was not an illusion.
At the same time, his conception did not occur through the ordinary union of man and woman. It was accomplished by divine power, without a human father. For this reason, the language of being “made” can emphasize the miraculous divine action by which his sacred humanity was formed.
The two expressions therefore emphasize different aspects of the same mystery:
Christ was born, because he truly received humanity from his mother.
Christ was made, because his conception occurred by the singular power of God rather than through male seed.
The virginal conception does not make Christ less human. It reveals that his human life is wholly the gift and initiative of God.
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13. Why David?
Paul identifies Christ specifically as descended from David rather than simply from Abraham.
Certainly, the promise was made to Abraham, and Christ belongs to Abraham’s line. But Aquinas gives two reasons for Paul’s emphasis upon David.
First, David reveals Christ’s royal dignity. David was the great king of Israel, and God promised that his throne would have an enduring fulfillment. By identifying Jesus as David’s descendant, Paul presents him as the promised king—the Messiah whose reign extends to all nations.
This would have carried particular significance for readers in Rome, the capital of an empire claiming dominion over the nations. The true universal king does not arise from imperial violence. He comes from David’s line and reigns through truth, holiness, sacrifice, and love.
Second, David gives hope to sinners.
Abraham stands prominently in Scripture as a man of faith and righteousness. David, although chosen and greatly loved by God, also committed grave sins. He received mercy through repentance.
Christ’s descent from David therefore bears a consoling message. God’s saving plan is not defeated by human sin. The Lord can bring the Savior through a family history marked by both sanctity and failure. Aquinas sees in Christ’s Davidic descent a reason for sinners to hope for pardon [Commentary on Romans (St. Thomas Aquinas) §1:40–41].
Jesus does not enter an idealized humanity untouched by shame. He enters our actual human history in order to redeem it.
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14. One God, one history, one Savior
These verses establish a profound unity.
The God who inspired the prophets is the Father of Jesus Christ. The Scriptures of Israel are holy. The promises of the Old Testament find their fulfillment in the Gospel. The eternal Son has genuinely entered the history of David’s family. The body he assumed was real, not imaginary [Commentary on Romans (St. Thomas Aquinas) §1:40–41].
There is therefore one divine plan stretching from promise to fulfillment:
God promises salvation.
The prophets bear witness to that promise.
The Scriptures preserve it.
The Son fulfills it.
The apostles proclaim it.
The Church receives it and hands it on.
Christianity cannot be severed from Israel’s Scriptures without becoming unintelligible. Nor can Christ be reduced to one more figure within the history of religion. He is the eternal Son in whom the promises reach their fulfillment.
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The heart of the Gospel
Romans 1:2–3 gives us the essential form of Christian faith.
The Gospel comes from God. It was promised through God’s prophets. It was preserved in the holy Scriptures. It concerns God’s own Son. This Son is eternally divine and truly human. He is one Person possessing both the divine and human natures. According to his humanity, he belongs to the royal line of David.
The Gospel is therefore both ancient and new.
It is ancient because it fulfills promises given across centuries. It is new because the fulfillment surpasses everything humanity could have imagined: the eternal Son of God has entered our history.
He did not come merely to speak about God from a distance. He came to unite humanity to God in his own Person.
Before the Gospel is a command, it is a gift. Before it tells us what we must do, it announces what God has done. The God who promised has remained faithful. The Word has entered our history, assumed our nature, and drawn near to sinners.
The Christian response begins in wonder, faith, gratitude, and adoration.
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Principal source
St. Thomas Aquinas, Commentary on the Letter of Saint Paul to the Romans, chapter 1, lecture 2, §§25–41.
Disclaimer
This article was written with the assistance of Catholic AI and is based principally on St. Thomas Aquinas’s Commentary on the Letter of Saint Paul to the Romans.