To know God is to know that God is good and shares good things. He has always been good and always will be good. And he has always shared his goodness and always will share his goodness.
And this means something important for the Christian life: despite any circumstance or any confusion on our part, God is always good and will always do good. We never have to question whether or not God has good intentions towards us; he does. By faith in his Son Jesus Christ, with whom the Father has shared all of his goodness, we too receive of that bounty.
And no feeling, no thought, no rational argument that we might produce can gainsay the truth about the good God who is eternally beneficient. That is what the doctrine of eternal generation is all about. So let’s take a few minutes to grasp this life-giving truth.
God is Father because he has a son (and vice versa)
God is Father because he has a son. If he had no Son, we would not know him as Father. Likewise, the Son is the Son because he has a father. These two names that stand at the centre of the identity of the Father and Son make sense only because the Father has a Son and the Son has a Father.
The simplest Bible passage to teach this is John 5:26: “For as the Father has life in himself, so he has granted the Son also to have life in himself.” The Father gives existence or life to the Son.
To understand how the Father and Son share life in themselves, we can look at passages like Colossians 1:15: “He is the image of the invisible God.” When we look into a mirror, we see an image of ourselves. When we move, our image moves. By analogy, when the Father looks at the Son, he sees an image of himself. When God moves, the Son moves.
The Father and Son relationship distinguishes the Father from the Son, but they also share a close relationship. When one moves, the other moves identically as an image does in a mirror.
By looking at the names of God such as the name Image from Colossians 1:15, we begin to learn that the Father has always projected his Image. The Son always generates from the Father and reflects the Father perfectly like an image in a mirror.
The Father begets the Son eternally, changelessly, and immaterially
When did the Father beget (an old word that speaks of childbirth) the Son? If we consider the question for a moment, then it starts to boggle our minds. We know that God is uncaused, infinite, and eternal.
The question of when when it comes to God is outside of the scope of our natural ability. We simply cannot conceive of what that might mean because we are caused, finite, and time-based. We do not know what it means to have no cause, no boundaries, and no temporality.
Yet the Bible claims that the Son has always been with God (John 1:1–3) and had the glory of God before creation (John 17:5). So we are pressed to understand how an eternal God can eternally speak his Word—or how the Father can eternally beget his Son.
God does not exist as we do. Since he is timeless, he cannot change. Change measures time. The earth rotates—one day. The earth orbits the sun—one year. The movement of the earth in both cases signifies what we call time: a day or a year. Time as an entity has no real existence. It is simply the measurement of change like an abstract tape-measure.
So to say God is timeless means that God is changeless. He does not grow smarter one day and stronger another day. So to beget a son could seem to imply some sort of lack in God—some need for change!
We also have to remember that God is immaterial. He is Spirit (John 4:24). The Father begat or generated the Son immaterially. When a cow gives birth to a calf, body begets body, fluid begets fluid. This sort of birth serves as an analogy. But again: it cannot tell us exactly what it means for a bodiless eternal being to beget.
What we do know is that God begat the Son in a changeless and immaterial way. It happened outside of the scope of our ability to comprehend since we are by nature material, temporal, and so changeable.
The eternal begetting of the Son is in God
We have to conclude that the Father has always begotten the Son. Theologians describe this relationship with the attributes filiation (from the Latin filius which means son) and paternity. It is how we can distinguish one from the other: one is Father and relates to the Son by paternity; the other is Son and relates the Father by filiation. This relationship bespeaks the inner-life of God. God is full of life which is his paternal and filial relations.
Nothing outside of God needs to enter into God. The Father has life in himself and shares it with the Son who in turn has life in himself (John 5:26). Since Father and Son are eternal, this has always been the case.
God eternally has shared of himself. He has given the Son all that he is: his life is in the Son. It is both their possession. All that God is is in the Son. God is love (1 John 4:8). God is holy (Isa 6). God is good (Mark 10:18). No shadow of evil or darkness is in him. He is constant in his goodness.
And remarkably, God by nature shares his goodness with the Son. He is always sharing it. He is beneficent.
And this is the best news that we could hear
God’s eternal generation is good news because it means that God reliably and always shares his goodness. He created the world and it was “very good” (Gen 1:31). He created humanity, and this was good. He sent his Son into the world because he by nature shares of himself. John writes, “For God so loved the world that he gave his only begotten Son, so that anyone who believes in him might not perish but have eternal life” (John 3:16).
Sometimes life can be so confusing and murky that we do not know what to think. Our knowledge of the Bible may be incomplete, and we might feel confused about what God would have us do. We might feel that God has hidden his face from us. We might feel empty, alone. We might feel almost any sort of dour emotion.
But this we can know unflinchingly: God is always good, always sharing his goodness, always beneficent. It is his kindness that leads us to repentance (Rom 2:4). And it is his goodness that means we can trust him unfailingly despite how we feel.