Christians speak of the Son as being “the only begotten Son” (John 3:16) from all time to give words to how they can confess the oneness of God and say: “To him who sits on the throne and to the Lamb be blessing and honor and glory and might forever and ever!” (Rev 5:13).
If God sired the Son from all time, then the Son’s filial relationship to the Father has always described their relationship. It was an eternal begetting or an eternal generation.
Recently a number of Christians have either denied eternal generation, supplanted it, or at the very least have redefined it. The new paradigm takes the name Eternal Relations of Authority and Submission (ERAS).
At least two major obstacles stand before ERAS. First, how can one God eternally obey the one God? That implies two wills. But God is one and so has one will. So he cannot obey his own will.
Second, and what I want to focus on here, ERAS does not articulate how the Spirit can be distinguished from the Father and Son. In short, it cannot explain our worship or liturgical practice of baptizing in the name of the Father, Son, and Holy Spirit.
The earliest Christians developed the key analogy to explain their worship by calling the Son, the Logos or the Word (John 1:1). As word follows thought and can be said to be ours and yet not quite the same as us, the Word of God is God and yet not quite the same as the Father.
Words immaterially proceed from a thinker. John speaks in this way about God to distinguish the Son from the Father and yet affirm both as the one God. Since God is invisible (John 4:24; Rom 1:20; 1 Tim 1:17; Col 1:15), then procession must be invisible too. And that’s why the Logos analogy usefully provides words for our worship.
The New Testament also hints at an analogy that likewise can explain the immaterial procession of the Holy Spirit, namely, that of love and the will to love (e.g., Rom 5:5).
As the Logos represents an immaterial procession of intellect, so Love (Spirit) represents an immaterial procession of will.
For a fuller presentation of how this works, consider reading my article on double procession here.
But the simple point that I want to make is this: eternal generation of the Word has a correlate in the eternal procession of Love.
These distinguishing properties give us the language to describe how we can worship in the name of the Father, Son, and Holy Spirit.
In contrast, ERAS defines the Father as authoritative and the Son is obedient in their eternal relationship. But the Spirit then seems to have to take the moniker of being eternally obedient to both Father and Son.
What other relationship can the Spirit have in the ERAS paradigm? I have yet to see any indication that ERAS distinguishes the Spirit beyond being sent from God; yet ERAS defines being “sent” when it comes to the Son as being obedient in his eternal relationship to the Father.
So the Spirit’s “sending” likewise seems to mean being obedient. And if both Son and Spirit are distinguished by “obedience,” then how are they different? The answer is they are not. And if they are not distinguished, then why do we worship a tri-unity and not a di-unity?
Eternal generation, the immaterial procession of Logos from God best explains how God is three yet a unity.