Read John 1:1–3
The hardest part of the Trinity for most people to grasp is that all three persons have always existed together. The Eternal Father, the Eternal Son, and the Eternal Holy Spirit are each fully God, and they are truly distinct from one another, yet there was never a time when any one of them did not exist.
Most of the pictures or comparisons we try to use fall short because they quietly introduce the idea of time, order, or ranking. They suggest that one person came first and another came later, or that one somehow gave existence to another. Scripture will not allow that. There was never a moment when the Father existed and the Son did not. The Father did not create the Son or bring Him into being at some point. The same is true of the Holy Spirit. The differences between them are real, but those differences have no starting point. They simply belong to who God is.
This is why the Bible speaks of the Son already being with the Father "in the beginning" and sharing glory with the Father "before the world was." Time and space as we know them had not yet been created. The relationship between the Father, Son, and Spirit came before anything else.
Because of this, explanations that try to make the Trinity easier by giving the Son or the Spirit a beginning usually end up treating them as less than fully God. Other explanations (modalism) that try to avoid the difficulty by saying the three persons are just different roles or appearances of the same person also fall short. Both approaches make the teaching simpler by removing something Scripture does not allow us to remove.
In the end, there is no ordinary human comparison that can fully explain how the Father, Son, and Spirit have always existed together. The response Scripture calls for is simply to accept what it says. The Father is eternal, the Son is eternal, and the Spirit is eternal. We are not expected to fully understand how that works. Our minds are shaped by a world that has time, beginnings, and sequences, so we should not be surprised that the eternal life of God is beyond our complete grasp.
So, what does it mean to be eternal?
To be eternal means to have no beginning and no end. This is how Scripture teaches us about the Godhead. It does not simply mean lasting a very long time. It means existing outside of time altogether; having no starting point and no point at which existence could come to an end. Therefore, we shouldn't really try to view the Godhead in any terms of existence. Even the Scriptures don't speak of God as "existing".
Time itself is part of the world God created. We see this first in Genesis chapter one. And so, the Creator is not one more thing that came into being inside time. He simply is. That's why He refers to Himself as "I Am". And this is why Scripture can speak of Him as the One who was, and is, and is to come. The Father, Son, and Spirit have always "existed" (shared glory) together because that is what it means for God to be God.
So, what does it mean to "share glory"?
When Jesus speaks of the glory He had with the Father "before the world was" (John 17:5), He is referring to the eternal life and relationship He shared with the Father before anything was created (by them together).
I thought glory had to do with splendor, fame, and radiant vastness?
It is to an extent. But it's more than that, it's about Their infinite worth, beauty, and perfection that belongs to God alone.
That last part is the hitch-pin. To say the Son shared glory with the Father before the world began is to say that the Son already fully possessed and participated in that divine life. Therefore "glory" belongs to Them alone. Jesus was not waiting to receive it. He was not becoming God. He was already with the Father, fully God, in perfect communion, together with the Spirit. The glory they share is not something that started at creation or at the incarnation. It is the eternal reality of who God is.
The apostles understood this:
Colossians 1:16–17
All things were created through the Son and for Him, and He is before all things.
Hebrews 1:2–3, 8–12
The Son is the one through whom God made the worlds; the Father addresses Him as God and applies to Him the language of everlasting existence.
But not only the Eternality of The Son, they also understood the Eternality of The Spirit.
Hebrews 9:14
…how much more will the blood of Christ, who through the eternal Spirit offered himself without blemish to God, purify our conscience from dead works to serve the living God.
And this understanding about the Eternal Spirit is all over the Old Testament:
Genesis 1:2
"the Spirit of God was hovering over the face of the waters"
The Spirit of God was already present and active at the very beginning of creation.
Psalm 104:30
"When you send forth your Spirit, they are created, and you renew the face of the earth."
The Spirit is understood to be the agent of creation and ongoing life.
Job 33:4
"The Spirit of God has made me, and the breath of the Almighty gives me life."
So, at the end of the day, what does the Trinity mean?
The Trinity means that there is one God who exists eternally as three distinct persons. the Father, the Son, and the Holy Spirit. All co-eternal. The word "trinity" itself means threeness. But it's not like saying God or the name of God. It speaks more to the nature of God. It's a term Christians use to summarize what Scripture teaches about God. It's pointing to God's word and what His word says about Him. In short, the Trinity is the confession that God is one in essence and three in person. It is not three gods, and it is not one person who sometimes acts as Father, sometimes as Son, and sometimes as Spirit. It is one God, eternally "existing" (so to speak) as Father, Son, and Holy Spirit.
Why is it right or wrong to refer to God as "existing"?
It's not right or wrong. It's a matter of distinction. There is an important difference between the way God exists and the way everything else exists. Created things exist because God gave them existence. God on the other hand has no beginning and no end. God does not receive His existence from anyone or anything.
I choose to avoid saying "God's exists" because God is the source of all existence. The very ground of all creation.
So, for me, when God says, "I Am" it means God simply is. I can't say He exists because He is infinitely beyond what we understand about existence. I avoid the existence question because ordinary language about "existing" falls short. Our categories of existence are shaped by things that begin, depend, and can cease. And this is in part why so many also struggle with the idea of the Trinity. We instinctively try to fit God into categories of existence that only apply to what He has made.
So, the only category I'll view the Godhead in is Eternal. Eternal Father, Eternal Son, Eternal Spirit.
God just is Eternal.
And I'm not.
Amen 🙏🏼