Solutions to Objections Against the Incarnation

Altar at the Church of the Annunciation in Nazareth. “The Word became flesh here.”

St. Thomas concludes the section on the Incarnation by solving the supposed metaphysical problems with it, which were posed earlier, in Chapter 40.

Summa Contra Gentiles, Book IV, chapter 49

The Holy Spirit and The Incarnation


We rightly attribute the Incarnation to the Holy Spirit.

Summa Contra Gentiles, Book IV, chapter 46

But Christ is not the “son” of the Holy Spirit.

Summa Contra Gentiles, Book IV, chapter 47

We cannot call Christ a “creature” without qualification.

Summa Contra Gentiles, Book IV, chapter 48

[Click HERE to catch up on previous chapters.]

Three SCG Chapters Touching on the Birds and the Bees

Now St. Thomas considers the formation of the Body of God Incarnate, in His mother’s womb. St. Thomas applies the doctrine about the divine Personality of Jesus to His hidden life as an unborn baby.

Leonardo da Vince Madonna and ChildAs we try to understand these chapters, we should remember that we have insights into the fertilization of a human egg by human sperm, as well as the formation of a human embryo and its development–insights that St. Thomas did not have.

In Chapter 43, St. Thomas makes an argument about the conception of the Christ that we would now say actually applies to every human being. St. Thomas recognizes that the logic of the Incarnation required that the divine Person be united with the conceived embryo at the moment of conception. Christ the embryo was a Person from the moment He came into being in the womb.

In order to understand St. Thomas’ first argument in Chapter 45, we have to keep in mind that the he did not hold this to be true for other human beings. St. Thomas thought that the embryo was “pre-human” and only became a human person with a rational soul–and a properly “human” body–at some later point in development, during pregnancy.

This explains St. Thomas’ remarks at the end of Chapter 44, where he speaks of the “quantitative” increase of the preternaturally “organized” prenatal Body of Christ. He is talking about the growth of the size of the baby’s body. In the saint’s mind, in human beings in general, that growth in size is not yet “human” until some later point during pregnancy.

Again, what St. Thomas maintains about Christ is actually true of everyone, as developments in science have taught us. The one-celled human conceptus does in fact possess the full “organization” of a human body, in the DNA. It is all just a matter of “quantitative” growth from there, with no change of substance or essence.

In Chapter 45, St. Thomas’ gets bogged-down in a controversy over whether or not the male supplies any “matter” in human conception. We can leave that aside and still appreciate the saint’s points about the power of the divine cause.

I dare you not to smile at the end of Chapter 45, when the Angelic Doctor makes a humbly manful distinction about what exactly causes a mother to lose her virginity.

Summa Contra Gentiles, Book IV, chapter 43
Summa Contra Gentiles, Book IV, chapter 44
Summa Contra Gentiles, Book IV, chapter 45

Christ’s Human Nature: God’s “Very Own Instrument”

Summa Contra Gentiles, Book IV, chapter 41


St. Thomas held an ax in his hand.

He saw an instrument that he could hand to someone else–the ax. And he saw an instrument that was “his very own”–his hand.

In Chapter 41, he proposes this distinction as a solution to the one-Person-with-two-natures problem.

How Can Christ be Human without Being a Human Person?

Vasily Surikov's painting of the Council of Chalcedon
The Council of Chalcedon, by Vasily Surikov


With Chapter 35, we begin a series of chapters that consider how divine nature and human nature can unite in one Person, the eternal Son of God.

This chapter explains the wrongness of Eutyches’ solution to this problem, which is known as the heresy of monophysitism. St. Thomas thoroughly explains what we mean when we refer to human “nature.”

Chap. 35 is just the beginning of St. Thomas’ treatment of the union-of-two-natures-in-one-Person problem. There’s more to come, so don’t be alarmed when the end of this chapter leaves you wanting more.

Summa Contra Gentiles, Book IV, chapter 35

One Person, with Two Natures

Summa Contra Gentiles, Book IV, chapter 34

Chapter 34 is one of three extra-long chapters in Book IV of St. Thomas’ SCG. Here he tackles Nestorianism.

First he gives a “steel man” outline of the heresy. Steel man as opposed to straw man. St. Thomas always gives his opponents’ arguments as much coherence as possible.

St. Thomas explains what Nestorianism tried to prevent: We should not attribute to God things that are incompatible with the divine nature, like suffering and dying.

Then St. Thomas points out the fundamental Scriptural problem with Nestorianism. He makes grammatical arguments against it. Then he carefully considers important New-Testament passages that touch on the problem.

Please keep in mind the unusual but crucially important term we considered when we read Chapter 5. A supposit is a particular instance of a type of thing. When the type of thing is “rational being,” St. Thomas also uses the Greek term hypostasis. Both supposit and hypostasis appear repeatedly in Chapter 34, since we are focusing on the particular rational being, the particular person, Jesus.

Chapter 34 leaves us with…

a. The Blessed Virgin Mary truly is the Mother of God.

b. The magnificent mystery of the  “communication of idioms.” That is, everything about the Christ, all the divine things and all the human things, can be ascribed to the one Person who is Jesus.

For example:

We can say–we must say–“God died.” Not because God died in His divine nature, but because He died in His human nature, which He assumed to His divine Self in the Incarnation.

And we can say “Jesus created the universe,” not because Jesus the man created the universe (Jesus the man is a creature) but because Jesus is, as a Person, the eternal Word, the Creator.

The Christian religion sits on this fundamental bedrock: the unity of the Person of the God-man, Jesus of Nazareth. In other words, we Christians, beginning with the Apostles, believe in the Incarnation.

The Human Flesh and Bones of Christ

Summa Contra Gentiles, Book IV, chapter 30

In this chapter, St. Thomas confronts the heresy that Christ’s body came from heaven, rather than from the Blessed Mother.

(The preceding chapter had already addressed the false presupposition of this idea, namely that all earthly things are completely evil.)


Then St. Thomas deals with the even weirder idea that the eternal Word became flesh by changing into flesh.

Summa Contra Gentiles, Book IV, chapter 31

The Holiness of Christmas

El Greco Nativity

We commemorate the birth of our Savior. His Nativity makes the long, cold night holy and bright. [Spanish]

The virgin Mary gave birth to the Savior in the humblest of circumstances, with the cattle lowing and the hay on the floor. The quiet humility of the people—the Child, His mother, St. Joseph, and the shepherds—that humility makes the night lovely. The loveliness of their humility begins to draw us into the holiness of the moment. But we have to go deeper into that holiness to identify it correctly. We have to find the path of humility ourselves.

We know that this poor family lives in intimate communion with the God of Israel. Mary and Joseph found themselves in the stable in Bethlehem, with a newborn child, in December, precisely because of their membership in the chosen nation.

They are descendants of king David, children of Abraham; they are praying Jews. Their kinsfolk Elizabeth and Zechariah lived a few miles away, not far from the Temple in Jerusalem. Zechariah ministered as a priest in that Temple, originally built by king David’s son.

Mary and Joseph had to travel to Bethlehem in the first place, and had to deal with spending the night of the child’s birth with the animals, because their people lived under the yoke of foreign occupiers. Mary, Joseph, and Jesus would have spent the night comfortably at home, if the children of Abraham were not subject to oppression. That was their nation’s history, beginning in Egypt.

This family’s chosen-ness as humble Israelites, then—that draws us into the holiness of the moment. But still we have to go deeper.

We know that the child born in the stable will become the wisest and gentlest of teachers. He will give His followers a body of doctrine, both classic and new. He will teach about religion, human relationships, justice, mercy, and the meaning of life. He will become the most-profound religious and ethical philosopher the world has ever known.

This fact makes us see the night of Christ’s Nativity as an “enlightenment” of the dark world. Jesus lived His teaching with perfect fidelity, total honesty and consistency. His whole life reflected what He taught. In fact, His consummate lesson was simply His life. He lived what He taught and taught us above all by how He lived.

Temple aroma

This convincing wisdom of the Savior helps us understand the spiritual radiance of the night of His birth. Still, though, we have not reached the heart of Christmas holiness.

The holiness of Christmas fundamentally involves this:

The Savior born on this night went to the cross. He offered Himself to the Father. His whole human existence led to His crucifixion. He died an innocent Lamb. He became a priest, and offered Himself, as a religious sacrifice on behalf of the whole human race, His people.

The sacrifice of Jesus of Nazareth saves us because it is both human and divine. For a man—even the noblest of men—to offer himself in death as an innocent victim of injustice—that would inspire us as an act of selflessness. That is precisely the case of the many martyrs that we venerate. But even the noblest self-offering of a human being cannot in itself save the human race from evil.

What happened with our Savior is: God became a human being, and offered His divine holiness, justice, and love, in sacrifice—as one of us. The eternal Word became flesh, and then He gave Himself back to the Father, as a man, for the salvation of all His human brothers and sisters. The unfathomable Trinity opened up to us, and drew us into the Eternal Love of the Father and Son, the Holy Spirit.

That is salvation. That is heaven opening, and grace pouring down upon us. Our salvation involves a divine human being, a human God. The dark, cold night of Christmas shines with radiant holiness because the cooing child is the infinite, incarnate Creator.

The Christmas mystery. The Person Who Jesus is. The mystery of the Incarnation silences the night because God’s grandeur surpasses our capacities of expression, even of thought. The holiness of the moment makes the whole situation perfectly simple. All we can do is worship.

God transcends us. He transcends everything. We know we cannot master God. Therefore, we cannot master Christmas, either. We cannot even fully fathom the word “Savior,” which we use to identify the Child. What we can do is believe. We can believe in the Incarnation precisely because it is God Almighty Who could and would make Himself one of us. We can call Jesus our Savior not because we understand what that means, but because we believe that Almighty God can and will save us.

Therefore, when we draw spiritually near to Bethlehem, we worship. We kneel before God in Christ. All praise, honor, glory, and majesty to Him, the Word of God made flesh for our salvation.