As an ancient discipline, theology uses old and unfamiliar words. Sometimes then, we find theological words hard to figure out. The word impassibility, for example, sounds strange to us.
Yet at its heart, impassibility means that God never stops loving you perfectly. No hunger, tiredness, or other ailments can prevent God from loving you fully and perfectly, ages without end. The doctrine means that God does not have created a body with nerves, needs, and necessities like drinking or eating. God is uncreated, of a different nature than we are.
Jesus says, “God is Spirit” (John 4:24). So we should not expect bodily tiredness to make God grumpy like what could happen to us. God can simply be Love (1 John 4:8). It also means we cannot hurt God by throwing a shoe at him. God is Spirit, and so we are unable to harm him bodily since he has no created body like us. He creates; we are created; and only creatures of created bodies.
There is another reason why this old-fashioned word should be kept, one often unstated but that stands at the very heart of orthodoxy, of Christian faith. The doctrine of impassibility helps us name the precise biblical truth about how the Father and Son relate to one another and how they share one divine nature.
How? Let me explain.
Arianism, A Heresy That Says Father and Son Do not Share One Nature
During the 300s, Christians debated how to worship God. In particular, they tried to find words that made sense of their worship of the Father and Son. Some opted to argue that the Father and the Son have different names and functions in the Bible, so they must differ naturally.
Others believed this view contradicted the Bible’s teaching. They argued that the Father and Son share one nature because both are God. Both create, and everything that does not create is a creature. So the Father and Son eternally beyond all space and time relate to one another by an eternal relation of fatherhood and sonship. Or to use the older language, the Son is eternally begotten of the Father.
This latter view won out against what history usually calls Arianism. Arians or more accurately the Eunomians of the fourth century argued that the Father and Son did not share one nature; they were unalike.
Basil of Caesarea (330–379) responded to this argument which was made by Eunomius of Cyzicus (d. c. 393). And the argument was not merely academic. As Basil wrote, “I think there is no doctrine in the gospel of our salvation more important than faith in the Father and the Son” (CE 2.22). If faith in Father and Son is that important, then we must know what it means to have faith in Father and Son for our salvation.
One way Basil made his case involved the doctrine of impassibility.
The Son is Impassibly Begotten of God
If God is impassible, he has no human body and so no blood or veins as we do. Instead, Basil argued we should think of the Bible’s language of begetting (e.g. John 1:18) in a way appropriate for God.
In human terms, a child is born in blood and water, in time, and after his parents. Human families are passible and corporeal (have created bodies). There is no other way. In the created order, parents precede children in time and place. But if God is beyond creaturely status—impassible and also eternal, then the Father begetting the Son must look different.
Basil explains, “Indeed it is clear to anyone who examines these names, I mean ‘Father’ and ‘Son,’ that they do not in their proper and primary sense naturally give rise to the notion of corporeal passions. On the contrary, when they are said by themselves they indicate only their relation to another” (CE 2.22).
Shortly after, Basil compares human fathers and sons with the divine Father and Son to develop his point. “So, then, when we hear that a man is a father, at that time the notion of passion occurs to us as well. But when we hear that God is Father, we reason our way back to the cause that is without passion” (CE 2.23).
Basil knows that this is hard to figure out. In fact, he affirms that we cannot comprehend God. God is infinite. We are finite.
He nevertheless warns, “It is inappropriate to refuse to believe in the impassibility of God because of attention to the passion of corruptible beings. And it is inappropriate to compare the immutable and inalterable substance with the transient nature that is subject to countless changes” (CE 2.23).
His point is that just because we are used to how things work for us as creatures of God, we should not think about God as being just like we are. Or else, we will deny things like impassibility and immutability (God does not change).
So let me get back to the main point
Father and Son are eternally God, Because of an Impassible Generation
If we follow Basil’s reasoning, we can say the following. The biblical names for God, Father and Son, do not point to the Father having a wife, who births a child in time and in blood and toil. Rather, these names tell us something about God without these implications because God is not a creature.
The names, as Basil says, “indicate only their relation to another.” Since God is impassible and so has no human body, then the names Father and Son tell us how Father and Son relate to each other. We call this doctrine eternal generation, an old word that means that God eternally was Father and Son because the Father eternally generates (or begets) the Son. The biblical names imply this relation, while various Bible verses describe eternal generation with all sorts of language (e.g. Heb 1:3; Col 1:15, etc.).
And if Father and Son have been in a relation of paternity and sonship before all ages, then Father and Son are before all times and change. They created. And so they are uncreated. And what is uncreated is God since the Bible says “All things were made through him, and without him was not any thing made that was made” (John 1:3).
If only God exists before creation, then Father and Son are both naturally God. They share the divine nature. They are eternally in a relation Fatherhood and Sonship, eternally God. Humans fathers and sons cannot share an eternal relation of fatherhood and sonship. They have bodies, are passible. Human fathers always precede in time their children. Not so with God because he is impassible.
The doctrine of impassibility then gives us the words to make sense of what the Bible says about God. It helps us to worship God with our minds.
If Basil is correct, the doctrine of impassibility not only tells us that God will never stop loving us perfectly despite our failings, but it also tells us that God is who the Bible says he is: Eternally Father and Son.
Note: I believe the Holy Spirit is divine too. But the point of my article was to discuss how impassibility tells us about the Father’s eternal generation of the Son.
