The Mysterious Doctrine of the Trinity – Acticle B: The True God
February 16, 1992 | Ray Pritchard
My introduction to the doctrine of the Trinity came at a very young age. I first learned it through the music we sang at the First Baptist Church. The great hymn “Holy, Holy, Holy” was number one in the Baptist Hymnal. Over the years the words “God in three persons, Blessed Trinity” were tattooed on my soul. Each Sunday we began the worship service by singing the Doxology, which ends with the words “Praise Father, Son and Holy Ghost.” It was good theology, but I never really knew what it meant.
In my early years I never heard an explanation of the Trinity.
It wasn’t proved … It was assumed.
It wasn’t explained … It was stated.
It wasn’t preached … It was sung.
That was true then and it is still true now. Except for a couple of classes in seminary, I have never heard a lesson on this subject. I have never heard a preacher try to defend it. For that matter, I’m not sure I’ve ever heard anyone try to deny it. And I can hardly remember anyone ever asking me about it.
The Trinity is the doctrine we all believe but never discuss. Either we all understand it, and therefore no discussion is needed, or none of us understands it, and therefore no discussion is possible. I cheerfully admit that I fall into the latter category. Although I am going to defend the doctrine of the Trinity in this message, I would not say that I understand it. I’m not sure anyone really does. But that doesn’t make it untrue. Most of the things we believe we don’t fully understand. Nowhere is that statement more true than when we come to speak of God himself.
Does It Really Matter?
Why is there so much confusion about this doctrine? Two reasons are immediately obvious. First, the very idea of the Trinity seems very mysterious. On the face of it, to speak of three persons and yet one God seems to be a contradiction. Perhaps you’ve seen the Jehovah’s Witnesses make fun of this doctrine by writing 1 + 1 + 1 = 3. They say that the Trinity is nonsense because it means that we believe in three gods. To be honest, many of us feel uncomfortable trying to answer that teaching because we can do basic math as good as anyone else. Second, the doctrine of the Trinity seems unimportant. So what if you believe in the Trinity and I don’t? We all believe in God, right? Isn’t that all that matters? I call this Phil Donohue theology: “We all worship the same God but we just call him by different names.” If you believe that, then it doesn’t matter whether the doctrine of the Trinity is true or not.
I. What Do We Mean By the Trinity?
Article B of the Calvary Memorial Church Articles of Faith is explicit on this point: “We believe that the Godhead eternally exists in three Persons, the Father, the Son and the Holy Spirit, and that these three are one God, having precisely the same attributes, co-equal and co-eternal.” That sentence contains a number of helpful affirmations concerning the Trinity:
1. The Trinity is an eternal truth about who God is.
2. The Trinity means that God exists as three persons—the Father, the Son and the Holy Spirit.
3. The Trinity also means that these three persons eternally exist as one God.
4. Since the three persons of the Trinity share precisely the same attributes, whatever may be said of one member of the Trinity may be said of the other two.
5. The members of the Trinity are equal in every respect.
6. All three members of the Trinity have always existed.
All of that may be boiled down to two statements:
1. God exists in Three Persons.
The Father who is the Creator
The Son who is the Redeemer
The Holy Spirit who is the Sanctifier.
2. These three are One God.
United in substance
Never any disagreement
Never any conflict
Never any division
Perhaps in illustration would help. You will not be surprised to know that the early Christians had a tough time with this doctrine. Many were converts from Judaism which held to an absolute monotheism (belief in one God). Others came from Greek and Roman backgrounds where they had worshiped many Gods. So some thought the doctrine of the Trinity went too far, while others thought it didn’t go far enough.
The history of the first few centuries of the Christian church is the story of a great struggle to define this doctrine. Three issues were central:
1. The unity of God
2. The deity of Christ
3. The personality of the Holy Spirit
By stressing the unity of God the early Christians struggled to answer the charge that they worshiped three Gods (a claim often laid against them by the Jews). At the same time they argued among themselves about the precise relationship between Jesus the Son and God the Father. Numerous theories were advanced, including the idea that Jesus was a mere man (the Ebionite view) or divine but still inferior to the Father (Monarchianism) or that Jesus became the Christ when he was baptized (Adoptionism). A man named Arius proposed that Jesus was the greatest of all created beings. His theology (Arianism) threatened for a time to destroy the Christian movement. It was condemned at the Nicea and again at Chalcedon. Finally, the church had to decide whether to consider the Holy Spirit as an impersonal force (an “it”) or a Person (a “he”). And if the Holy Spirit was a Person, how was he related to the other two Persons in the Godhead?
To read the story of those ancient conflicts is to learn of men like Tertullian, Origen, Athanasius, the Three Cappadocians, Nestorius, Sabellius and Paul of Samosata. Some were condemned as heretics while others helped formulate the orthodox doctrine of the Trinity. To those of us who regard the doctrine of the Trinity with a yawn, it may come as a surprise to know it took the Christian church nearly 500 years to settle the issue.
II. The Athanasian Creed
Finally a creed was composed in or about the year A.D. 500 which has come to be regarded as the definitive statement on the Trinity. J.N.D. Kelley gives the following estimate of the theological value of the Athanasian creed:
No other official document or creed sets forth, so incisively and with such majestic clarity, the profound theology implicit in the New Testament affirmation that “God was in Christ reconciling the world to himself.” (Cited in Creeds of the Churches, p. 704)
Although the precise circumstances surrounding the writing of the creed are unknown, it has become the most widely-accepted statement of the doctrine of the Trinity. It is one of the few statements about which all Christians agree. The Athanasian Creed is accepted by Catholics, Baptists, Lutherans, Presbyterians, Mennonites, Methodists, Nazarenes, and all the various branches of the Orthodox church. In fact, we could go so far as to say that if you don’t believe what the Athanasian Creed teaches, you are outside the boundaries of the Christian faith.
It is not necessary to quote the entire creed in order to pick up its essential teaching. The following segment gives a flavor of its teaching:
Now this is the Christian faith, that we worship one God in Trinity and Trinity in unity, without either confusing the persons or dividing the substance. For the Father’s person is one, the Son’s another, the Holy Spirit’s another; but the God-head of the Father, the Son and the Holy Spirit is one, their glory is equal, their majesty co-eternal. (Creeds of the Churches, p. 705)
The Creed goes on to state that the Father is almighty, the Son almighty, the Holy Spirit almighty, “yet these are not three almighties, but one almighty.” Similar statements are made concerning deity: “Yet there are not three Gods, but there is one God.” To show the seriousness of the issue, the Creed says, “Thus in all things, as has been stated above, both Trinity in unity and unity in Trinity must be worshiped. So he who desires to be saved should think thus of the Trinity.” (Italics mine)
Although that final statement has been criticized as virtually identifying true Christianity with intellectualism, it shows how crucial the doctrine of the Trinity had become. It was one of the watershed issues for those who wished to be called Christian. If you did not accept this doctrine, you would not be welcomed into the Christian church.
The key statement of the Athanasian Creed is “Trinity in unity and unity in Trinity.” That statement is further defined by two crucial clauses:
1. Neither confusing the Persons—The Father, Son and Holy Spirit are three distinct Persons within the Godhead. You don’t mix the Father up with the Son, or the Son with the Holy Spirit, or the Holy Spirit with the Father.
2. Nor Dividing the Substance. The term “substance” refers to whatever it means to be God. It’s the essence of “God-ness.” All three Persons fully possess the”substance” of “God-ness.” All three are fully God. No one Person is more God than another. This statement also means that you can’t divide or split the Trinity. This was a specific answer to those who held to Monarchianism, Arianism, Adoptionism or any form of Subordinationism. The Father is not somehow “more God” than the Son or the Spirit. The Son is in no way less than fully God. The Spirit is just as much God as the Father and the Son. The “substance” cannot be divided.
III. Three Useful Analogies
Admittedly this is a difficult doctrine to understand. Even when you study for many hours you are left with your head spinning. That’s why Christians have looked for analogies to explain what the Trinity is like. Unfortunately, some of the analogies (like water appearing as ice, liquid and steam) actually come closer to illustrating heresy. What we are need are analogies that help see plurality and unity at the same time. The following may help in this regard:
1. The universe is an illustration of the Trinity.
Dr. Henry Morris suggests that the nature of the universe reflects the Trinitarian nature of God. He points out that the universe (a unity) is made up of space, matter and time. Everything in the universe falls into one of those three categories. All three are necessary for the universe to exist and none of the three could exist without the other two. Furthermore, each one of the three is itself a trinity. Space consists of length, width and breadth. Matter consists of energy, motion and phenomena. Time consists of past, present and future. Our universe is thus a trinity of trinities! Dr. Morris concludes his discussion with these words:
There seems to be a basic system of three-in-oneness pervading the whole creation. While these facts cannot be held to prove that the Creator of the universe and of life is a triune being, it is certainly to formulate any other hypothesis as satisfactory as this to account for the existence of such universal triunity in nature. The doctrine of the Trinity is no unscientific, primitive absurdity, but intensely scientific and a tremendously important living reality. (That You Might Believe, pp. 38-39)
2. Human nature is an illustration of the Trinity.
J. Oliver Buswell, in his Systematic Theology of the Christian Religion (pp. 124-126), suggests that we have a hint of the Trinity in the complexity of human nature. For instance, I am one person yet I may debate with myself. As I debate within myself, I can listen to both sides of the argument and come to my own conclusion. It is all “me” yet there are various conscious “parts” of me involved in the whole process. As Dr. Buswell points out, this is but a faint shadow of the doctrine of the Trinity, but the illustration is not without its uses. While not explaining the Trinity, “it does show at least that we are not contradicting ourselves when we teach what the Scripture teaches about God, namely, that God being infinite in all of His perfections is complete, Triune, in subsistence.” (p. 125)
3. Marriage is an illustration of the Trinity.
If there is any biblical illustration of the Trinity, this is it. In marriage, two distinct persons join together to become “one flesh.” Remember, that phrase comes directly from Genesis 2:24. Something happens in the act of marriage that creates a new entity, a new being, a new being that was not there before. The two persons are still individual and unique and yet they are united in a “one-flesh” relationship. They are two but they are also one. That’s why Christian marriage at its best illustrates the very nature of God. That’s also why Paul used the same illustration in Ephesians 5 to explain the mysterious relationship between Christ and the church.
IV. Three Heretical Views
Not surprisingly, such a difficult doctrine has inspired a host of heretical counterfeits. Throughout church history, three heretical views have surfaced time and again.
False View # 1: The Trinity equals three Gods.
This objection was first made by the Jews in their response to the teaching that Jesus Christ was the divine Son of God. They felt that to hold to a plurality of persons in the Godhead was to effectively abandon monotheism. In later generations, the same claim was made by various unbelievers as a way to discredit Christian teaching. In the 20th century, the Jehovah’s Witnesses are most noted for making this argument. As I noted earlier, the Jehovah’s Witnesses like to reduce the Trinity to a mathematical formula: 1 + 1 + 1 = 3. That objection, while appearing formidable, is really just a smokescreen. Who says you have to add the Persons of the Godhead? Why not multiply them? Then the equation becomes 1 x 1 x 1 = 1. But that only shows the futility of reducing God to numbers on a piece of paper. When the doctrine of the Trinity is properly formulated, it lays equal stress on both sides of the biblical evidence: One God eternally existent in three Persons.
False View # 2: The Trinity means one God in three forms.
This is the very ancient heresy called modalism. It is basically the idea that there is only one God who appears in different “modes” or “forms” at different times in history. Like a player putting on a mask, God appears sometimes as the Father, sometimes as the Son, sometimes as the Spirit. But this view denies that there really are three distinct “persons” in the Godhead. In this view, the Father is the Son, the Son is the Spirit, the Spirit is the Father. After vigorous debate, the early church rejected modalism because it tends to downplay the uniqueness of Jesus Christ by making him little more than a “mode” or “form” of God rather than God incarnate in human flesh. In its attempt to stress the idea of the oneness of God, modalism neglects the clear biblical evidence for the Father and the Son and the Holy Spirit. That’s why the Athanasian Creed specifies that you must not “confuse the Persons” of the Trinity (which Modalism does).
False View # 3: The Trinity means Jesus is inferior to the Father.
This view is similar to modalism in that it attempts to protect the oneness of God by devaluing the uniqueness of Jesus Christ as the Son of God. The most common form of this teaching in the early Church was Arianism—which suggested that Jesus Christ was a created being (and not the eternally existent Son of God). This view finds currency in various modern cults—such as the Jehovah’s Witnesses (who say that Jesus is Michael the Archangel) and the Mormons (who are essentially polytheistic). The New Age Movement does the same thing by suggesting that Jesus was “a” (not “the”) Son of God, one of many avatars or highly-evolved beings to come to the earth. This view also gave birth to the Unitarian movement.
At this point it would be useful to stress that any doctrine of the Trinity must balance two crucial elements: 1. The oneness of God. 2. The plurality of Persons with the Godhead. The heresies mentioned above originate in an attempt to stress one part of the biblical evidence at the expense of the other part. Sometimes heresy begins simply because well-meaning people feel uncomfortable with a doctrine they cannot completely understand; sometimes it starts because theologians want to remove the tension between oneness and plurality. Yet in their attempts to make the Bible more “understandable” or “logical” or “coherent” or “non-contradictory” they have ignored its real teaching and ended up worshiping a God who is quite simply not the God of the Bible.
V. Biblical Evidence For the Trinity
That brings us at last to the crucial question: What is the biblical evidence for the doctrine of the Trinity? If it is true, where do we find it in the Bible? In answering those questions, we can begin with a simple observation: The word Trinity is never found in the Bible. You can look it up in the concordance but you won’t find it there. But just because the word isn’t found in the Bible doesn’t mean the doctrine isn’t found there. The basic principle we must follow is to take all the Bible statements about God’s basic nature at face value. When we do that, we find evidence for oneness, evidence for threeness, and evidence for three-in-oneness. By carefully putting all the evidence together, and without slighting any part of the evidence in favor of other evidence, we arrive at the orthodox doctrine of the Trinity.
In completing this section, I am leaning heavily on notes prepared by my Associate Pastor, Brian Bill. Pastor Bill begins his treatment of the biblical evidence with these helpful comments:
Any concept of the Trinity must be carefully balanced, for it must maintain on the one side the unity of God, and on the other side the distinctness and equality of the Persons. Ryrie suggests the word Triunity is better since it contains both ideas — the “tri” (the threeness) and the “unity” (the oneness).
A. Evidence for Oneness
Consider the following verses:
Exodus 20:3 “You shall have no other Gods before me.”
Deuteronomy 6:4 “Hear, O Israel: The Lord our God, The Lord is one.”
Isaiah 45:18 “I am the Lord, there is no other.”
James 2:19 “You believe that there is one God. Good!”
These verses are representative of dozens that might be quoted from both testaments. The Bible is completely clear on this central point: There is one God and he alone is worthy of our worship, praise, adoration and obedience.
B. Evidence for Threeness
Consider these representative verses:
1. The Father is God
John 6:27 “God the Father”
Galatians 1:1 “God the Father”
2. The Son is God
John 1:1 “The Word was God.”
John 8:58 “Before Abraham was, I am.”
John 10:30 “I and the Father are one.”
John 10:28 “Thomas said to him, ’My Lord and my God.’”
3. The Holy Spirit is God
Acts 5:3-4 “You lied to the Holy Spirit … You lied to God.”
Again, examples could be multiplied in all three categories. The bottom line is this: The New Testament repeatedly says things about the Son and the Holy Spirit that could only be true of God himself. By ascribing the attributes of God directly to the Son and to the Spirit, the writers are teaching us that the Son and the Spirit are not simply “like” God but are as much God as the Father is.
C. Evidence for Three-in-Oneness
In this category we find several crucial passages where all three Persons of the Trinity are brought together in complete equality.
1. Matthew 28:19
“Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit.” Note that all three Persons are mentioned together. Note also that the unity of God is strongly suggested by the singular “name” (and not “names”). Note also that there is no hint of inferiority or subordination of the Son and Spirit to the Father. One name — Three Persons.
2. Matthew 3:16-17
“As soon as Jesus was baptized, he went up out of the water. At that moment heaven was opened, and he saw the Spirit of God descending like a dove and lighting on him. And a voice from heaven said, ’This is my Son, whom I love; with him I am well pleased.’” Note that all three Persons are present at the baptism of Jesus—the Father (the voice from heaven), the Son (who was being baptized) and the Spirit (descending like a dove). Again, there is equality and differentiation of Persons at the same time without any hint of inferiority of one Person to the others.
3. Two Trinitarian Statements
“May the grace of the Lord Jesus Christ, the love of God, and the fellowship of the Holy Spirit be with you all.” II Corinthians 13:14
“Chosen according to the foreknowledge of God the Father, through the sanctifying work of the Spirit, for obedience to Jesus Christ.” Note that in both cases, although different terminology is used and a different order of mention is made, there is a basic equality among the three Persons of the Trinity. The writers of the New Testament clearly felt free to mention all three together in the same verse without any further explanation.
4. The Gospel of John (from George Hendry,The Holy Spirit in the Christian Theology, p. 31)
Finally, consider carefully the evidence from the Upper Room Discourse of Jesus. In John 14-16 our Lord repeatedly shows the close interrelationships between the Father, the Son and the Holy Spirit.
1. The Son is sent by the Father (14:24) and comes forth from him (16:28).
2. The Spirit is given by the Father (14:16) , sent from the Father (14:26), and proceeds from the Father (15:26).
3. Yet the Son is closely involved in the coming of the Spirit; he prays for his coming (14:16); the Father sends the Spirit in the Son’s name (14:26); the Son will send the Spirit from the Father (15:26); the Son must go away so that he can send the Spirit (16:7).
4. The Spirit’s ministry is understood as a continuation and elaboration of that of the Son. He will bring to remembrance what the Son has said (14:26); he will bear witness to the Son (15:26); he will declare what he hears from the Son, thus glorifying the Son (16:13-14).
When all the biblical evidence is fully considered, we find two facts which must somehow be balanced in our thinking: A. There is only one God. B. He eternally exists in three co-equal and co-eternal Persons. We must hold these two facts together because the Bible does. If we slight either part of the truth, or downplay one side in favor of the other, our doctrine will inevitably end up less than biblical.
Millard Erickson ( in his Christian Theology, p. 342) offers the following very helpful summary:
The doctrine of the Trinity must be divinely revealed, not humanly constructed. It is so absurd from a human standpoint that no one would have invented it. We do not hold the doctrine of the Trinity because it is self-evident or logically cogent. We hold it because God has revealed that this is what He is like. As someone has said of this doctrine: Try to explain it, and you’ll lose your mind; but try to deny it, and you’ll lose your soul.
VI. The Practical Value of this Doctrine
The Trinity has been called “the fundamental doctrine of Christianity,” “the sum and total of our faith” and “the central doctrine we must believe.” This doctrine has been believed across the centuries by orthodox Christians of every variety. Furthermore, those who have attacked it have found their attacks answered vigorously and gladly. Believing in the Trinity joins us with the saints of every age. We join the Christian army when we believe this doctrine. Although we differ with our fellow believers on points both major and minor, we quickly set aside lesser things when we declare that this doctrine is true and we will defend it. Seen in that light, the Trinity is a doctrine of unity for believers across the ages and around the world.
But that’s not all. Whenever unbelief has entered the church, it has eventually attacked this doctrine. Sometimes the Trinity is attacked directly, sometimes indirectly, but heretics always end up here. That should tell us something, shouldn’t it? The Trinity must be an important doctrine if those who reject our faith have denied it.
It is obvious that Jews do not believe this doctrine, nor do Muslims—although Jews and Muslims will often have a high opinion of Jesus Christ. Yet they cannot, will not, take the crucial step of calling him the Son of God. The Jehovah’s Witnesses do not believe it, nor do the Mormons or the Unitarians. New Agers deny this doctrine as do the Christian Scientists and the spiritualists.
Sometimes a doctrine is known by its enemies as well as by its friends. The Trinity is important because so many people who are going to Hell go out of their way to deny it.
But what is the practical value of this doctrine?
1. It tells us what God is like.
First of all, the Trinity tells us that God is personal. Secondly, it tells us that God is a God of fellowship. God didn’t create the world because he was lonely. Before the universe came into being the three Persons of the Godhead knew each other in perfect harmony. The world was not created because of some “lack” in God’s nature. The world was created because God wanted the human race to share the perfect fellowship with him that he had from all eternity within his own being. If that seems to be speculative, we are left with Augustine’s answer to someone who asked him, “What was God doing before he made the universe?” Answer: “He was creating Hell for people who ask questions like that.” Admittedly, there are many mysteries here, but the Trinity suggests that God is a God of personal love and fellowship—aspects of his being which were expressed even before the world was created.
2. It tells us what the death of Christ means.
How else could we conceive of One dying for the sins of the world? A mere man could not do that. If Christ is not fully God, then his death is not a substitution for the sins of mankind. To the contrary, if Christ is merely human—or even slightly less than fully God—his death is nothing more than a martyr’s death, the sad story of a good man who meant well but came to a bad end. But if Christ was God incarnate—if he really was the “Word made flesh”—then and only then could he redeem the fallen human race. Only One who is infinite as God is infinite could suffer the infinite pains of eternal separation from God. No mere man could do that. No demi-god could do that. No half-man, half-god could do that. Only One who was fully Man and fully God could suffer as a man and as the Son of God at the same time. Without the Trinity his death has no meaning and our salvation is only an illusion.
3. It tells us what the Christian life is like.
Through the Trinity we learn that our God is a personal God who is able to have rich personal fellowship within his own being. That’s what the Christian life is all about: An invitation to rich personal fellowship with the Triune God. I John 1:3 brings both sides together. “We proclaim to you what we have seen and heard, so that you may have fellowship with us. And our fellowship is with the Father and with his Son, Jesus Christ.” Here is fellowship presented on three levels—Fellowship between believers, fellowship with the Father and fellowship with the Son. J. Oliver Buswell paints a beautiful picture of what this means:
We should be overwhelmed with the brilliance of the thought that God, who is Himself a God of love and fellowship, created us for fellowship with Himself. Think of the infinite possibilities of the future, the vistas of infinite riches of love, and knowledge, and personal development, which lie before us in God’s eternal kingdom. (Systematic Theology, p. 129)
Salvation comes to us from the Father, through the Son, by means of the Holy Spirit. As all three Persons of the Godhead are involved in our salvation, we are invited to enjoy intimate personal fellowship with God the Father, God the Son and God the Holy Spirit.
Greater Than We Will Ever Know
The great conclusion is this: The Trinity is known only because God himself revealed it to us. We could never imagine such a thing on our own. It is a mystery in the biblical sense—something unknown to us until God chose to reveal it to us.
—But it is not irrational or illogical
—It is not unimportant
—It is the truth of the Bible.
We love God precisely because he is greater than we are. If we understood him completely, he would not be God. If we knew him as he knows us, we would not love him so much. Because he is greater than us, we may spend our entire lives learning about him and still never exhaust the knowledge of God.
Holy, Holy, Holy, Lord God Almighty
Early in the morning our songs shall rise to Thee.
Holy, Holy, Holy, Merciful and Mighty
God in three Persons, Blessed Trinity.
Two Additional Questions
1. Is it wrong to pray to the Holy Spirit?
John R. Rice has a helpful answer to this question:
It is a mistake to put too much emphasis on whether one should pray to the Father or to the Son or to the Holy Spirit. In the Lord’s Prayer we are taught to address the Father. But during His earthly ministry, many prayers were addressed to the Lord Jesus. Stephen, in his dying prayer, prayed to Jesus, saying, “Lord Jesus, receive my spirit.” Again he prayed, “Lord, lay not this sin to their charge.” Paul, at his conversion, prayed to Jesus.
So why should one not pray to the Holy Spirit? God is a Spirit. And Father, Son and Holy Spirit are one. What one does, they all do. What one knows, they all know. There could be no jealousy among the Trinity. (Dr. Rice, Here is My Question, p. 164)
I should add that many of our favorite hymns are prayers to the Holy Spirit: “Spirit of God, Fill Me Now,” “Breathe on Me” and “Spirit of the Living God, Fall Afresh on Me.” Others hymns switch Persons between the verses: “Search me, O God” begins with the Father but in the second verse address the Son—”I praise Thee, Lord, for cleansing me from sin”—and concludes with a verse addressed to the Holy Spirit—”O Holy Ghost, revival comes from Thee.” In addition, we often sing “Father, I adore you,” then “Jesus, I adore you” and “Spirit, I adore you.” If it is proper to sing to all three Persons of the Trinity (and I believe it is), then we should have no trouble praying directly to the Father or to Jesus or to the Holy Spirit, according to the need of the moment.
2. Does the Old Testament contradict the doctrine of the Trinity?
The answer to that question is a simple No. But if you ask, Does the Old Testament directly teach the doctrine of the Trinity?, the answer would also be No. A more precise answer would be that the Old Testament anticipates the later New Testament revelation of the Trinity. For instance, there are hints of the Trinity in the very first chapter of Genesis. When Genesis 1:1 says, “In the beginning God created the heavens and the earth,” the word for God is Elohim, which is technically a plural form in Hebrew. Genesis 1:2 mentions the Spirit of God hovering over the waters of the deep. In Genesis 1:26 God says, “Let us make man in our own image.” But verse 27 says, “God created man in his own image.” Is this a contradiction? Not at all. Verse 26 corresponds with the New Testament idea of plurality while verse 27 presents the idea of unity. Furthermore, when Deuteronomy 6:4 says, “The Lord is one,” the particular Hebrew word for “one” (echad) means “one in unity.” Moses didn’t use yachid, the Hebrew word which means “an absolute one.” Echad is the same word for “one” used for marriage in Genesis 2:24—”The two shall become one flesh.” Proverbs 30:4 strongly implies that God has a son, while Isaiah 48:16 appears to name all three Persons of the Godhead in one verse.
All of this is not to say that Moses or any of the prophets understood the Trinity. They didn’t. But under the inspiration of the Holy Spirit, God was described in terms that included both plurality and unity. These hints and implications would later be developed into the doctrine of the Trinity. What is anticipated in the Old Testament is fully revealed in the New Testament.