Foundations Lesson 3: What is the Trinity?

Updated: Feb 5, 2020

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The Doctrine of The Trinity

When I hear the word Trinity, my heart often skips a beat. Not in confusion but in doxology. Every aspect of Christian life is bound up in the glory of the triune Majesty, the Father, Son and Holy Spirit. If God the Father had not set his eternal love upon me through his eternal Son Jesus, and had not Jesus purchased my redemption according to the plan of the Father, and had not the Holy Spirit interjected into my life to unite me to Jesus by working faith and love for him in my heart, then I would have been utterly lost. If the Trinity were not daily working on my behalf, then I would be lost! If the Father was not daily accepting me because of the work of Christ, not hearing my prayers and working all to my good for his glory, then I would be lost. If the Son was not interceding on my behalf for my good as he reigns in glory, if the Holy Spirit was not stirring my heart in conviction for sin and affection for God and aiding my prayers for my good and his glory, I would be lost.


When you pray, do you know that you interact with each person of the Trinity? Do you know that when you pray to the Father, in the name of the Son, in the power of the Holy Spirit, each person is at work at that moment? Think of the security of your salvation for a moment. The Father has planned and determined that all who trust in the Son will have eternal life, and the Son has promised that he will never cast out those who come to him. The Holy Spirit was given to us by the Father and the Son as a down payment to assure us that we are eternally secure in the hands of the triune God. This is a lot of theology, and we’ll be talking about things that sometimes might seem a tad abstract. Abstract things are difficult because they seem to have no practical value, but in learning about God this is never the case. We are worshippers of God meaning the passion for God that invades our minds and hearts by God himself bridges theology to doxology. Knowledge of God breaks into song, but often first breaks into silent reverence. As we come close to the burning bush, personal priorities and pragmatism meet transcendence and priorities become reordered around the Holy One. Theology, knowledge of God, is not an add-on to our already set and determined lives, but in fact should shape and determine the lives of those who worship God. It is not just meant to help us with our priorities, but to shape them.


Contours of the Trinity

Now what is the Trinity? We use the term somewhat frequently, but what are we talking about? The New City Catechism says, “There are three persons in the one true and living God: the Father, the Son, and the Holy Spirit. They are the same in substance, equal in power and glory.” This can be slightly confusing. It can even sound a bit weird, but I think a word from Kevin DeYoung could be helpful. Kevin wrote the devotional for this section of The New City Catechism. Here’s what he said to introduce the doctrine with his usual clarity and wit: “The doctrine of the Trinity is the most important Christian doctrine that most people never think about. It’s absolutely essential to our faith, and yet for many Christians it just seems like a very confusing math problem. And even if we can figure out what ​Trinity​ means, it doesn’t feel like it has much bearing on our lives, much relevance to us.

“The word ​Trinity​, famously, is not found in the Bible, but the word does very well at capturing a number of biblical truths. There are actually seven statements that go into the doctrine of the Trinity:

1. God is one. There’s only one God.

2. The Father is God. 3. The Son is God. 4. The Holy Spirit is God.

5. The Father is not the Son.

6. The Son is not the Spirit.

7. The Spirit is not the Father.

“If you get those seven statements, then you’ve captured the doctrine of the Trinity- what it means when we say there is one and three persons. Christians are monotheists. We don’t believe in many gods or a pantheon of gods but just one God, and this God expresses himself and exists as three persons. That language of ​persons​ is very important. The early church wrestled with the appropriate language, and ​persons​ aptly speaks to the personality of the three members of the Trinity and also their relationship with each other; the Father, Son, and Holy Spirit coinhere as one essence, and yet there are distinctions. One is not the other, but they’re equal in rank, equal in power, equal in glory, equal in majesty. Just as Jesus sends out the disciples to go baptize in the name of the Father, and of the Son, and of the Holy Spirit, we see this doctrine of the Holy Trinity woven throughout the Scriptures.


“Even more confusing to people is the question “Why does this even matter? Okay, I understand I got three in one, one in three. What difference does this make for anything in my Christian life?” In good Trinitarian fashion, I think there are three important things that the doctrine means for us. First, the Trinity helps us to understand how there can be unity in diversity. This is one of the most pressing questions in our world. Some folks focus almost exclusively on diversity, on the fact that people are so different. They don’t see any common ground. Others want to press for complete uniformity in thought, in government, and in expression. The Trinity shows us that you can have a profound, real, organic unity with diversity, so that the Father, Son, and Holy Spirit are working in complete union in our salvation. The Father appoints. The Son accomplished. The Spirit applies. We encounter God as fully God in the Father, in the Son, and in the Holy Spirit. And yet, their divine work is neither interchangeable nor redundant. Second, when you have a triune God, you have the eternality of love. Love has existed from all time. If you have a god who is not three persons, he has to create a being to love, to be an expression of his love. But Father, Son, and Holy Spirit existing in eternity have always had this relationship of love. So love is not a created thing. God didn’t have to go outside of himself to love. Love is eternal. And when you have a triune God, you have fully this God who is love. Finally, and most importantly, the doctrine of the Trinity is crucial for the Christian because there is nothing more important in all the world than knowing God. If God exists as one God in three persons, if the one divine essence subsists as Father, Son, and Holy Spirit, if we are baptized into this triune name, then no Christian should want to be ignorant of these Trinitarian realities. In the end, the Trinity matters because God matters.”


Understand those seven statements and you’ve captured the doctrine of the Trinity. If you were to pick up your Bible, find a concordance and search for the word “Trinity”, you would not find it. Critics of the Trinity, which we term heretics, are very keen on pointing this out but not very good at telling us why it matters. The word has for centuries been used to capture the biblical idea that God is three persons. Tri- means three and –une means in one being. Thus, triune means three persons in one being. B.B. Warfield commented a century ago, “The term “Trinity” is not a Biblical term, and we are not using Biblical language when we define what is expressed by it as the doctrine that there is one only and true God, but in the unity of the Godhead there are three coeternal and coequal Persons, the same in substance but distinct in subsistence. A doctrine so defined can be spoken of as a Biblical doctrine only on the principle that the sense of Scripture is Scripture. And the definition of a Biblical doctrine in such unbiblical language can be justified only on the principle that it is better to preserve the truth of Scripture than the words of Scripture.”


God has revealed the doctrine of the Trinity to give us an understanding of who he is. No one found this out or found it under a rock in the Middle East, rather this teaching comes from God’s own testimony about himself. What we see in this doctrine is that there is one true and living God, one divine being. Besides him there is no other. And, yet there are three persons in this one divine being. The Father is God, the Son is God and the Holy Spirit is God. However, the Father is distinct from the Son, the Son distinct from the Father and the Holy Spirit is distinct from the other two. Each person, though equally divine in being, is yet distinct in personhood. We can call these facets and biblical underpinnings to the doctrine of the Trinity.


An analogy from James White that I always thought was helpful was that if I pick up a book, it has no personhood. It is not a ‘who’. But, if I pick up the same book and throw it at you, you better believe it has being. Personhood is what makes you who you are. God is one being, but he is three persons. There is a mystery here for sure, but it is actually in some ways a very simple doctrine that opens our eyes to an incredibly overwhelming perspective of God that stretches our minds in some of the details, but the basic doctrine is quite easy. I remember listening to a debate between Christopher Hitchens, a famed atheist now passed away, and Pastor Douglas Wilson. Christopher claimed that the Trinity is simply not understandable.

Doug responded, “Well, black holes exist and they are quite hard to understand.”

Christopher said, “Well, I can draw a black hole on the board quite easily.”

Doug responded, “I can draw the Trinity on the board, too, with a triangle and a circle.”


The Biblical Data

To me one of the most exciting things to do in studying the Bible is seeing the Trinity. There have been several occasions when I was reading and was struck by the Trinity. For instance, I was reading and meditating on Ephesians 1 when it hit me that each section in the chapter was divided by a person of the Trinity. The Father elects and predestines us to adoption; the Son accomplishes redemption for the elect, and then the Spirit indwells the elect as a down payment of salvation, until they are raised from the dead on the last day. It just blew me away that Paul was such a Trinitarian, and that it was simply presupposed in his mind. He couldn’t help but think in that way.

Here are the three main points from scripture:


1. There is one God: The Father, The Son and The Holy Spirit are identified as God. Each Divine person is distinct.


We are monotheists. We believe in one divine being. We explored this a bit in the last lesson, but it might be helpful to go over a couple of these truths. Deuteronomy 6:4-5 shouts monotheism. There are not many gods, polytheism. There’s one God and he’s our God, the God who made himself known in scripture. He’s not a god who reigns over one sphere here or there. He’s the God of the hills and of the valleys.


In Isaiah 44:6-8, God says, “Divinity: mine! By nature and right to which no one else can lay claim”. God alone is God. Today we face more pluralism than polytheism, pluralism being the idea that there are many, a plurality of paths and ways to worship God. But, the core doesn’t change a whole lot when God lays claim to his own exclusivity in being, and exclusivity of worship. Only God is God and is to be worshipped as such.


The Father, the Son and the Holy Spirit are identified as God.

The monotheism of God is triumphed and declared throughout the Old Testament, but by the time we arrive in the New Testament, something drastic has happened. God the Son, Jesus Christ, has entered into his own creation. The incarnation has happened, and then the Holy Spirit came during Pentecost. Jesus had promised another helper would come who would empower the church and work in and through her, and be the presence of Jesus with the church. In these two events, the incarnation of the Son and the outpouring of the Holy Spirit, the Triune God made himself known. So, by the time the New Testament was being written, they were recording the events they had already experienced. In a sense, when we’re reading the New Testament, we can read things like Eph. 4:6 and it seems to be a creedal statement for the Church. In fact, each person of the Trinity is listed here. Paul cites it as an argument for unity, so there seemed to already be some truth known about the Father, Son and Holy Spirit. Think, why would Paul, if the Trinity was a controversial doctrine still being developed, cite it as an appeal to unity? 1 Cor. 8:4-6, in fact is actually quite stunning. “​Therefore, as to the eating of food offered to idols, we know that “an idol has no real existence,” and that “there is no God but one.” ​​For although there may be so-called gods in heaven or on earth—as indeed there are many “gods” and many “lords”— ​​yet for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist.​”


B.B. Warfield commented on this passage, “In the very act of asserting his monotheism Paul takes our Lord up into this unique Godhead. “There is no God but one," he roundly asserts, and then illustrates and proves this assertion by remarking that the heathen may have "gods many, and lords many," but "to us there is one God, the Father, of whom are all things, and we unto him; and one Lord, Jesus Salutations Conclusions Monotheism that includes the Son and the Spirit of Christ, through whom are all things, and we through him" (I Cor. 8:6). Obviously, this "one God, the Father," and "one Lord, Jesus Christ," are embraced together in the one God who alone is. Paul's conception of the one God, whom alone he worships, includes, in other words, a recognition that within the unity of His Being, there exists such a distinction of Persons as is given us in the "one God, the Father" and the "one Lord, Jesus Christ." In Matt 28:16-19, “​Go therefore and make disciples of all nations, baptizing them in[​b​] the name of the Father and of the Son and of the Holy Spirit​”. Jesus teaches his disciples to baptize in the name(singular) of the Father, Son, and Holy Spirit. One name, three persons united under one banner.”


B.B. Warfield comments again, “In seeking to estimate the significance of this great declaration, we must bear in mind the high solemnity of the utterance, by which we are required to give its full value to every word of it. Its phrasing is in any event, however, remarkable. It does not say, "In the names [plural] of the Father and of the Son and of the Holy Ghost"; nor yet (what might be taken to be equivalent to that),"In the name of the Father, and in the name of the Son, and in the name of the Holy Ghost," as if we had to deal with three separate Beings. Nor, on the other hand, does it say, "In the name of the Father, Son and Holy Ghost," as if "the Father, Son and Holy Ghost" might be taken as merely three designations of a single person. With stately impressiveness it asserts the unity of the three by combining them all within the bounds of the single Name; and then throws up into emphasis the distinctness of each by introducing them in turn with the repeated article: "In the name of the Father, and of the Son, and of the Holy Ghost "(Authorized Version). These three, the Father, and the Son, and the Holy Ghost, each stand in some clear sense over against the others in distinct personality: these three, the Father, and the Son, and the Holy Ghost, all unite in some profound sense in the common participation of the one Name. Fully to comprehend the implication of this mode of statement, we must bear in mind, further, the significance of the term, "the name," and the associations laden with which it came to the recipients of this commission. For the Hebrew did not think of the name, as we are accustomed to do, as a mere external symbol; but rather as the adequate expression of the innermost being of its bearer. In His name the Being of God finds expression; and the Name of God - "this glorious and fearful name, Jehovah thy God" (Deut. 28:58) -was accordingly a most sacred thing, being indeed virtually equivalent to God Himself. It is no solecism, therefore, when we read (Isa. 30:27), "Behold, the name of Jehovah cometh"; and the parallelisms are most instructive when we read (Isa. 59:19):' So shall they fear the Name of Jehovah from the west, and His glory from the rising of the sun; for He shall come as a stream pent in which the Spirit of Jehovah driveth.' So pregnant was the implication of the Name, that it was possible for the term to stand absolutely, without adjunction of the name itself, as the sufficient representative of the majesty of Jehovah: it was a terrible thing to 'blaspheme the Name' (Lev. 24:11). All those over whom Jehovah's Name was called were His, His possession to whom He owed protection. It is for His Name's sake, therefore, that afflicted Judah cries to the Hope of Israel, the Saviour thereof in time of trouble: '0 Jehovah, Thou art in the midst of us, and Thy Name is called upon us; leave us not' (Jer. 14:9); and His people find the appropriate expression of their deepest shame in the lament, 'We have become as they over whom Thou never barest rule; as they upon whom Thy Name was not called' (Isa. 63:19); while the height of joy is attained in the cry, 'Thy Name, Jehovah, God of Hosts, is called upon me' (Jer. 15:16; cf. II Chron. 7:14; Dan. 9:18, 19). When, therefore, Our Lord commanded His disciples to baptize those whom they brought to His obedience "into the name of . . . ," He was using language charged to them with high meaning. He could not have been understood otherwise than as substituting for the Name of Jehovah this other Name "of the Father, and of the Son, and of the Holy Ghost"; and this could not possibly have meant to His disciples anything else than that Jehovah was now to be known to them by the new Name, of the Father, and the Son, and the Holy Ghost.”


We find other astonishing Trinitarian passages in the New Testament such as 2 Cor. 13:14 “The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all​.​”​ 1 Cor. 12:4-6 “Now there are varieties of gifts, but the same Spirit; ​5 ​and there are varieties of service, but the same Lord; ​6 ​and there are varieties of activities, but it is the same God who empowers them all in everyone.” Spirit, Lord and God signifies three persons, but only one God.


Throughout the New Testament, the Father, the Son and the Holy Spirit are each identified as God.

Understanding the Father as God is simply not controversial to most people. Jesus says to the Father in John 17:3, “You the only true God” and Paul speaks throughout his letters of “God the Father of our Lord Jesus Christ” as in Ephesian 1:3. The deity of Jesus is usually where the debate happens, as with the doctrines of the Jehovah’s Witness. However, in the New Testament there really isn’t any debate.


John 1:1 “In the beginning was the Word, and the Word was with God, and the Word was God.”​ ​This is one of the best scriptural teachings on the deity of Jesus. I’m going to give a spoiler: Later in the text, the Word is revealed to be Jesus, the Son. The text lets us know three things about the “Word” (Logos in Greek) or we could just say the Son. First the word is eternal, from the beginning. “Was” indicates being without becoming, in other words eternality. John later contrasts the Word as becoming flesh. The words in Greek are ‘eimi’ and ‘ginomai’. The Son, the Word, always was ‘eimi’ in eternity but now in history becomes ‘ginomai’ flesh that is, and adds the human nature to the divine person of the ‘Logos’.


Second, the Word was with God. In other words the Word was in fellowship with and in the presence of God. We see here that God and the Word are in some sense, distinct from one another and yet both share an eternal relationship. If we keep reading the prologue, we see that God and the Word being discussed are the Father and the Son. The Son, Jesus, is the Logos, and he eternally was in relationship with the Father. The last part which is so crucial is that the Word was God. A different way to say this is that the Word was what God was in essence and being. The Son and the Father share the same divine being, and yet are distinct in persons. To recap, the Word is eternal, distinct from the Father in person and yet shares the same divine being as the Father.


Now, the Greek in John 1:1 is incredible in acute meaning. If John wasn’t careful, he could have said “the word was a god” which is by the way what the Jehovah’s Witness Bible says and is a terrible translation. If the scripture had said that the Word was ‘a god’ (which it doesn’t), the Word would be a kind of lesser god. So, we would have Arianism. If it said, “God is the Word”, then there is no distinction between the Father and Son, which is Sabellianism. But, instead he tells us that the Word and God share the same nature; the Father and Son are one in nature, yet distinct in person.


At the end of John 1 at verse 18, we see this explicitly. Both John and Peter, two of Jesus’ closest disciples, have no problem calling him God. In 2 Peter 1:2, Peter doesn’t find it weird or different to speak of his old rabbi as “God.” In Hebrews 1, we have even greater testimony to the deity of Jesus. Now Jesus is identified as the supreme manner of God’s self-revelation, the one who is sustaining the universe and also the accomplisher of redemption in verses 1-3. But, then in the two quotations that the author of Hebrews makes, he is being as explicit as possible. He is called God. A text that we actually looked at quite a bit last week concerning the doctrine of God is applied to the Son. We drew from Psalm 102 the eternal, infinite and unchangeable nature of th