The Trinity—also called Triunity or three persons contained in one God—is who God is in his fullest united, one essence.

Let’s being with a popularizer of theology and philosophy.

C.. S. Lewis encourages us not to wish and beg for a shallow religion. In his book Mere Christianity, in the chapter “The Invasion” he discusses the Incarnation (God the Son becoming man), which can also apply to the Trinity.

He writes:

It is no good asking for a simple religion. After all, real things are not simple. They look simple, but they are not. The table I am sitting at looks simple: but ask a scientist to tell you what it is really made of—all about atoms and how the light waves rebound from them and hit my eye and what they do to the optic nerve and what it does to my brain—and, of course, you find that what we call “seeing a table” lands in mysteries and complications which you can hardly get to the end of.

God is knowable as far as he has revealed himself through Jesus Christ, the Scriptures, the Holy Spirit who lives in us, and other avenues like the creation. However, no one has seen God in all of his full essence and being, except Jesus (John 1:18). We humans down here on earth are limited by our five senses and our finite minds, so how can we figure out and calculate the pure nature of God? “We can know God truly and sufficiently, but never comprehensively” (EDT, p. 343).

One reason that I believe in the Triunity is precisely because this doctrine is ultimately beyond my puny brain to figure out. I could never have invented it.

I simply have to accept Scripture as it is, even when I don’t understand all of it.

I trust God in the teachings I do understand (e.g. God loves me and saved me), and that leads me to trust him in the ones that I don’t understand completely (the Trinity).

It is best to go from known and simple things to the lesser known and difficult things. For example, it is best to study astrophysics and send out space ships over time before landing a human on the moon. Gradual. But unlike the moon landing, we will never understand the Triunity fully.

From simple and clear teachings to the deeper teachings is best the best route to travel.

To wrap this up, the deepest relationship between the three persons cannot be known by us in its fullest sense—it is not possible to contain the ocean in a thimble. But we can know him sufficient for our salvation and we can know him in truly—we know him in truth. But we cannot know him exhaustively—it would take eternity to accomplish it!

You already relate to the Father and the Son and the Holy Spirit. The articles on the Trinity at this website will help you put the doctrine together. Our God is Triunity—three persons in one essence, one God.

Get to know each person of the Trinity!

So how does knowing about the Trinity help me know God better?

Here is an entire ten-point post that answers that question:

The Trinity: What Does He Mean to Me?

For now: personally, I like to simplify things. The Scriptures reveal the Father and the Son, not to give us a headache, but so we can relate to them. We can have a personal relationship with the Father as intimately (and more so) as we have with our own father. And we can relate to the Son as the Messiah and Lord, who has a unique relationship with the Father. The Son reveals the Father. The title Father is more personal and revealing than “God.” The Spirit of the Father and the Son now lives in us so he can empower us to have a relationship with the Father and the Son.

May the grace of the Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit be with you all. (2 Cor. 13:14, NIV)

Bottom line: let’s have a relationship with the Father and the Son (and the Holy Spirit), since they are revealed in Scripture in those two persons (and the third person of the Spirit), for our relational benefit.

ARTICLES IN THE TRIUNITY SERIES

The Trinity: What Are the Basics?

The Trinity: What Are Key Terms?

The Trinity: What Are Some Illustrations?

The Trinity: What Does the Old Testament Say?

The Trinity: Three Persons Together in the New Testament

The Trinity: What Do Theologians Say?

The Trinity: What Are His Roles in Creation and Redemption?

The Trinity: What Does ‘Only Begotten Son’ Mean in John 3:16?

The Trinity: What Do Arians and Jehovah’s Witnesses Teach?

The Trinity: What Are Defective Ideas?

The Trinity: What Are Replies to Objections?

The Trinity: Why Would God Seem So Complicated?

The Trinity: What Does He Mean to Me?

SOURCES

Evangelical Dictionary of Theology, 3^rd ed., ed. by Daniel J. Treier and Walter A. Elwell (Baker Academic, 2017).

C.. S. Lewis, Mere Christianity (Touchstone, 1943, 1996).

Works Cited

Addendum

Elmer Towns came up with this table, which shows that each person of the Trinity shares the same attributes as one God:

SOME COMMON ATTRIBUTES OF THE TRINITY
Attributes	Father	Son	Holy Spirit
Omnipresence (Everywhere)	Jer 23:24	Matt 28:20	Ps. 139:7-12
Omnipotence (All Powerful)	Rom 1:16	Matt 28:18	Rom 15:19
Omniscience (All Knowing)	Rom 11:33	John 21:17	John 14:26
Immutability (Unchanging)	Mal 3:6	Heb 13:8	Hag 2:5
Eternality	Ps 90:2	John 1:1	Heb 9:14
Holiness	Lev 19:2	Heb 4:15	Name “Holy”
Love	1 John 3:1	Matt 9:36	Name “Comforter”
This list is far from exhaustive. Careful! Christ in his human nature was limited, but not in his divine nature (Towns p. 100)

Elmer Towns came up with this table too, which shows all three persons doing works that only God can:

THE WORK OF THE HOLY TRINITY
Work	Father	Son	Holy Spirit
Creation of World	Ps 102:25	John 1:3	Gen 1:2
Creation of Man	Gen 2:7	Col. 1:16	Job 33:4
Death of Christ	Is 53:10	John 10:18	Heb 9:14
Resurrection of Christ	Acts 2:32	John 2:19	1 Pet 3:18
Inspiration	Heb 1:1-2	1 Pet 1:10-11	2 Pet 1:21
Indwelling of Believers	Eph 4:6	Col 1:7	1 Cor 6:19
Authority of Ministry	2 Cor 3:4-6	1 Tim 1:12	Acts 20:28
Security of Believer	John 10:29	Phil 1:6	Eph 1:13-14
This shows the unity of the Trinity. Each person of the Trinity contributed to each of these wonderful works, to God’s glory and for our salvation and redemption (Towns p. 100)