Introduction to the Trinity
The doctrine of the Trinity is one of the most important doctrines of the Christian faith. And, one of the most challenged and sometimes ridiculed beliefs that Christians profess to believe. This article serves as a basic introduction to the Trinity. We hope you will find it a helpful and clarifying place to begin understanding the Trinity, and that you will appreciate its importance to your faith and worship.
Why Does the Trinity Matter?
Jesus said:
“Now this is eternal life, that they know you, the one true God and Christ Jesus whom you’ve sent.” - John 17:3
Being a Christian isn’t just about escaping hell, going to heaven, or becoming a better person. First and foremost, it’s about knowing God. It’s about being with God, and relating to God, and enjoying God as our greatest goal and reward. This is why the Westminster Shorter Catechism opens with this question and answer:
Question: What is the chief end of man?
Answer: The chief end of man is to glorify God, and enjoy him forever.
Since glorifying and enjoying God is life’s goal, striving to know and enjoy God more in this life should be our highest joy and aim. What does this have to do with the Trinity? Everything! Because God is the Trinity. Trinity is both what and who God is. So, knowing God means knowing the Trinity. As Scott R. Swain puts it:
“Learning to know the triune God, to receive the triune God, to rejoice in the triune God—and learning to help others do the same—is an end in itself, because the triune God is the ultimate end of all things. (Romans 11:36)”[1]
Scott R. Swain
In short, since God is the Trinity, knowing the Trinity is life’s greatest goal.
Why Do We Call God “Trinity”?
The word trinity isn’t in the Bible. It was first used to refer to God by a second century theologian named Tertullian. (c. 155 – 220 AD) In his written work titled Against Praxeas, Tertullian opposed Praxeas’ argument that Son, and Holy Spirit were just names attributed to the different roles that God the Father played in acting toward us. Tertullian refuted Praxeas by demonstrating how Scripture affirmed that Father, Son, and Holy Spirit weren’t just names, but three distinct persons eternally relating to each other within the Godhead. And so, he used the Latin word trinitas, meaning three, to describe the three-ness of God’s unified nature. Hence Trinity.
What Does “Trinity” Mean?
In simple terms, when we call God, the Trinity, we are simultaneously affirming three basic, biblical truths about God.
- There is only one, true God.
- The one true God exists as three, distinct persons: Father, Son, and Holy Spirit.
- Each person is fully God.
There is much, much more that the Bible tells us about the Trinity, but it never tells us less than this. Which is to say that these three statement make up the bare minimum facts about God’s nature as Trinity.
A Common Objection
People often object that affirming the above three statements constitutes a logical contradiction. “God can’t be ONE and THREE at the same time! That’s absurd!!” But is it? Are Christians left with no choice but to believe that 1+1+1=1, despite what logic and common sense tell us? No, we’re not.
There’s no question or debate that the Trinity is a mystery we can’t fully explain. We are talking about God, after all. But mystery doesn’t mean contradiction. And the doctrine of the Trinity isn’t a contradiction because it’s not saying that God is ONE God and THREE Gods. Nor is it affirming that God is ONE person and THREE persons. Trinity means ONE God who exists as THREE persons. The following diagram has been used by the church for many years to help make this distinction clear.
So, the doctrine of the Trinity isn’t affirming a logical contradiction. Rather, it’s expressing an eternal mystery of the only true God who is one in his being, but three in his persons.
Is the Trinity Biblical?
Just because the word Trinity, or the statement: “there is one God who exists as three persons” isn’t in the Bible, doesn’t mean the Trinity isn’t biblical. Just as the Bible progressively reveals the unfolding will of God, the doctrine of the Trinity doesn’t come from any one passage or section of the Bible either. Rather, it comes from a careful study of the whole revelation of Scripture.
In what follows, we will uncover the biblical evidence for the three bare-minimum truths about the Trinity mentioned above. In doing so, we hope that you will begin to see how the Bible doesn’t just support the doctrine of the Trinity. It makes it inescapable.
1. There is only one God.
The Bible is most clear that there is only one God. Genesis 1:1 tells us how God is the Creator who created everything else. And as the Creator, God stands alone. He is holy, which means he unified in his being, utterly unique, and distinct from all that he has made.
That’s why the first prayer the Israelites taught their children, called the ‘shema’, says: “Hear, O Israel: The Lord our God, the Lord is one.” (Deut. 6:4) Since God is holy, only God should be worshipped (Exodus 20:3). And, therefore, he is not to be confused with any created thing. (Exodus 20:4-5). God is majestic in his holiness, and awesome in glory (Exodus 15:11). This means nothing exists that is of greater goodness, beauty, or worth than God. God is equal to his own existence, which means he does not depend on anything else for his being. This is why God expresses his personal name to Moses as YHWH (lit. “I AM”). God is the self-existent one, which speaks to both his being and person.
“The name YHWH signifies God’s self-identity or simplicity (Ex. 3:14). God is identical with his existence (John 5:26) and his attributes (1 John 1:5); from age to age, he is the self-same, eternal and unchanging (Ps. 102:27)”[2]
Since God’s name expresses who he is, there is no greater name than God’s name. Which is why God says: “I am the LORD (YHWH); that is my name! I will not yield my glory to another or my praise to idols.” (Isaiah 42:8) There is no other god besides him, and so he says: “I am the LORD (YHWH), and there is no other; apart from me there is no God.” (Isaiah 45:5)
The Bible could not be clearer. From start to finish it consistently declares that there is only one God.
The Bible could not be clearer. From start to finish it consistently declares that there is only one God. Critics often argue that the doctrine of the Trinity threatens this biblical truth. On the contrary, as we will see, the absolute one-ness of God’s being is what provides the strongest biblical argument for the Trinity.
2. God exists as three, distinct persons: Father, Son, and Holy Spirit
In the Bible, the three-ness of the Trinity isn’t expressed quite as explicitly as God’s one-ness. However, through the progressive revelation of Scripture, its truth is clearly expressed throughout the Bible.
God’s Three-ness in the Old Testament
Admittedly, the triune nature of God is somewhat veiled in the Old Testament. The Jews certainly did not think of God as Trinity. And yet the words they spoke about God often hinted at God’s triune nature. For example, in the Old Testament God is presented as the Creator God who creates by his Word and through his Spirit (Gen. 1; Psalm 33:6, 9; Job 33:4). And, God sends forth his Word and his Spirit to accomplish his purposes. (Ps. 147:15, 18; Zech. 4:6)
At times, the wisdom of God’s Word speaks almost as another agent alongside God. (Proverbs 8) As does God’s Word on occasion through angel-messengers who appear in various instances to speak “the Word of the LORD”.
God’s Holy Spirit is also personified and acts with agency. (1 Kings 22:24; 2 Kings 2:16; Ezek. 11:5) As when David asks God not to take his Holy Spirit away from him. (Ps. 51:11-13). And, when Isaiah speaks about the Holy Spirit being “grieved” by Israel’s rebellion. (Is. 63:10)
In addition, Genesis 18 tells us that when the LORD (YHWH) visited Abraham, he appeared in the form of three men. (Gen. 18) At times God speaks about himself using the singular I/me (Genesis 9:9). But other times he uses the plural we/us. (Gen 1:26; 3:22; 11:7). And, sometimes he uses both, as in Isaiah 6:8.
“Then I heard the voice of the LORD saying, ‘Whom shall I send? And who will go for us?” (Isa. 6:8)
There are also instances in the Old Testament where God seems to be speaking to himself, as in Psalm 110:1 – “The LORD says to my Lord: Sit at my right hand until I make your enemies a footstool for your feet.” And, there are some curious occurrences of God’s name being repeated three times in a blessing (Numbers 6:24-26), or revered as three-times holy, as in Isaiah 6:3.
To be sure, none of these provide a “slam dunk” for a fully formed doctrine of the Trinity, but they do provide evidence of an undeniable “three-ness” in the way God revealed himself in the Old Testament.
God’s ‘Three-ness” in the New Testament
Though the Trinity is somewhat veiled in the Old Testament, the New Testament makes it much more apparent. The grammar and vocabulary of the New Testament church is decidedly trinitarian, established in Jesus’ parting command for how God’s new people, the church, should be identified.
“ 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,” (Matthew 28:19)
In the Old Testament, God’s people were identified as those called by God’s name. (2 Chron. 7:14; Isa. 43:7) The church is no different in this regard, except that now Jesus’ command equates God’s name (singular) with three names, Father, Son, and Holy Spirit.
And it makes sense that Christians are identified as God’s people in the name of the Trinity since salvation itself is the work of the Trinity. As Paul says in Galatians 4:4-6:
But when the fullness of time had come, God [the Father] sent forth his Son, born of woman, born under the law, 5 to redeem those who were under the law, so that we might receive adoption as sons. 6 And because you are sons, God [the Father] has sent the Spirit of his Son into our hearts, crying, “Abba! Father!”
In short, salvation occurs because God the Father sent God the Son to redeem us, in order to adopt us as his children through God the Holy Spirit. And so, throughout the New Testament the gospel is the good news of the Trinity’s saving work.[3]
Throughout the New Testament the gospel is the good news of the Trinity’s saving work.
But does this imply that the New Testament church truly understood the Father, Son, and Spirit as each being equally God? A careful look at Scripture will show that they did.
God the Father
There is little question that Jesus and his disciples considered the Father to be God. When Jesus spoke to God, he consistently called him Father. And when he taught his own disciples to pray, he told them, “when you pray, say ‘Our Father in heaven’”.(Matthew 6:9) On the day of Pentecost, Peter stood up and said to the Jews that Jesus had been exalted to the right hand of God, and “received from the Father the promise of the Holy Spirit”, whom he had now poured out on his disciples. (Acts 2:33) And Paul blesses God saying, “Blessed be the God and Father of our Lord Jesus Christ”. (Eph. 1:3)
But God’s fatherhood is not ultimately rooted in his creating or saving relationship to us. It is eternally rooted in his relationship to his eternal Son. God is our Father because he is the eternal Father. (1 Cor. 8:6) He is the eternal Father because he eternally begets his Son whom he loves. (John 1:1, 14; 18; 17:24) And as eternal Father, God the Father gives life to all. (John 5:26)
God the Son
Jesus made specific claims that show us he understood himself to be the divine Son of God on equal standing with God the Father. He said that just as the Father has life in himself, he has granted the Son to have life in himself. (John 5:26) He said all that is the Father’s is also his. (John 14:24) And, whoever had seen him had seen the Father. (John 14:9) Jesus said, “I and the Father are one”, (John 10:30), for which the Jews tried to stone him, accusing him of blasphemy for making himself equal to God. (Jn. 10:33). He said he was in the Father, and that the Father was in him. (John 14:10-11) Most astonishingly, to the Jews who were listening, Jesus claimed pre-existence to Abraham while claiming God’s name, “I am” (YHWH) as his own. (John 8:58) Again, for what they considered blasphemy the Jews tried to stone him.
Some look at all these statements made by Jesus and say that they merely reflect the very close relationship that Jesus enjoyed with God the Father. Groups like the Jehovah’s Witnesses consider Jesus to be God’s divinely created Son who was given all these divine gifts and privileges after God created him. But this is not how the apostles understood it.
When Jesus said “I and the Father are one”, he meant it literally.
They said the Son existed in the form of God, sharing “equality” with God; (Phil. 2:6) that he is “the Word” and “the image of the invisible God” in whom is life, and through whom all things were created; (John 1:1-3; Col. 1:15) that he is “the fulness of God” in bodily form; (Col. 2:9) that he is the “light of the knowledge of God’s glory” (2 Cor. 4:6), and the “radiance of God’s glory and the exact representation of his being, sustaining all things by his powerful word.” (Heb. 1:3) When you read statements like these, you realize that the Son cannot be a created being. Because if God the Father is eternal, then so is his Word, and his image, and his glory, and his radiance. Jesus can only be these things if he is equal with the Father. So, when Jesus said “I and the Father are one”, he meant it literally.
God the Holy Spirit
The Bible consistently presents the Holy Spirit as God’s power in action. We could say that it’s the Father who wills, the Son (the Word) who declares what the Father wills, and the Holy Spirit who accomplishes the Father’s will. In Genesis 1, for example, it’s the Holy Spirit of God who sovereignly hovers over the waters of uncreated chaos, ready to enact the Father’s creating will the very instant the Son (the Word) says, “let there be…” (Gen. 1) Throughout the Old Testament, on too many occasions to count, God enables his designated servants and prophets to accomplish his will or declare his word by sending his Holy Spirit upon them. And God himself testifies that everything he accomplishes according to his will he does so “by my Spirit.” (Zech. 4:6)
But God’s Spirit is not some invisible force or mere label for God’s power. The Holy Spirit is a person. He is God’s own Spirit who knows God’s own thoughts because he has God’s own mind. (1 Cor 2:11). God’s Spirit makes the church into God’s household because God lives in us “by his Spirit”. (Eph 2:22) In Acts 5 Peter equates lying to the Holy Spirit with lying to God. (Acts 5:3) And Paul warns us to avoid all sin which would “grieve the Holy Spirit.” (Eph. 4:30)
God’s Spirit is not some invisible force or mere label for God’s power. The Holy Spirit is a person.
But the Holy Spirit is also a distinct person from the Father and the Son. He is sent by both the Father (John 14:26) and the Son, (John 15:26) and therefore is not identical to them. And his purpose and goal are to glorify the Son, (Jn. 16:14) not by speaking from himself but only by taking from what he hears from the Father and the Son. (Jn. 16:13-15)
Hopefully you are beginning to see how inescapable the Trinity is. The more we discover of God from Scripture, the more clearly his triune nature becomes apparent. But there is one more important point that needs including in a biblical understanding of the Trinity. That is, in what sense all three are God.
3. Each person is fully God.
Does the Bible really affirm that the Father, Son, and Holy Spirit are each fully God? This is a critical question to answer. You might even say it’s the glue that holds together the tension between the first two truths. Establishing this might take a bit of effort, but it’s well worth it.
There are two key pillars that uphold the truth that the Father, Son, and Holy Spirit are each fully God.
Pillar 1: There is only one God.
Since there is only one God, when the Bible appears to identify the Father, Son, or the Holy Spirit as God, the Bible is rejecting any suggestions that multiply God. In other words, God’s “God-ness” (i.e. divinity) isn’t some quality or attribute that the Father, Son, and Holy Spirit all possess individually in equal measure. As God says through Isaiah, “there is none besides me; I am the LORD, and there is no other.” (45:6) and, “My glory I will not give to another.” (48:11)
Since there is only one God, and he does not share his glory with any other, when we say that the Father, Son, and Holy Spirit are equally divine, we mean that God has a single, unified divine nature, and that the Father, Son, and Holy Spirit each fully possess God’s one, unified, divine nature.
Pillar 2: God’s simplicity.
The truth of God’s simplicity begins with his personal name, “I AM” (YHWH). (Exodus 3:14) His name means that He is the self-existent one. God depends on nothing and no one for his existence. This is sometimes referred to as God’s aseity. This means God does not need his creation, or any other cause to be who and what he is.
Because God is self-existent and uncaused, it follows that God is simple, which means that God is not made up of parts. Michael Reeves explains why.
“Divine simplicity means that, just as God does not depend on anything outside himself, so in himself he does not have any parts he depends on in order to be who he is. In other words, God does not derive his being from any quality or idea or thing that might pre-exist him. There is no feature of God that predates him.”[4]
Michael Reeves
Perhaps a simple illustration might help make the importance of God’s simplicity clear. Consider a simple mousetrap. It’s made of five essential parts: a base, a spring, a hammer, a holding bar, and a trigger. Assembled together, all five parts make up the mousetrap. But prior to their assembly all you have are useless parts. The mousetrap doesn’t exist until the parts are assembled. In this sense, the existence of the mousetrap is dependent upon the assembly of the parts. Without their assembly, there is no mousetrap.
This is why theologians argue that God is simple in his being, which is to say he is not made up of parts. If, for instance, we thought of the Father, Son, and Holy Spirit as being three parts of God making up the whole, then God’s being would depend upon the assembly of those parts. His existence would depend upon something other than himself. But as the great “I AM”, God does not depend upon the assembling together of his persons, or his attributes and properties in order to be who and what he is. Rather, “all that is in God simply is God.”[5] So, God isn’t composed of a handful of attributes like love, goodness, and holiness that he might exhibit, sometimes more or less depending on his mood. Rather, God is love. God is good. God is holy. (1 Jn. 4:8; Mark 10:18; Lev. 19:2) These are equal to his being. Likewise, God is Father, Son and Holy Spirit, and each are equal to his being. Each are fully God, with the only distinction between them being their relationship to each other.
Conclusion
In this article, we’ve sought to lay out in a systematic way a basic framework for understanding the doctrine of the Trinity. Our goals have been first, to clarify for you exactly what the doctrine of the Trinity affirms and deny what it doesn’t. Second, to help you defend the doctrine of the Trinity as God’s true self-revelation that is clearly taught in the Bible. Third, since Jesus defined eternal life as knowing God, to help you clearly and confidently learn to know God as Trinity. Ultimately, so that you can grow in your knowledge of God’s glory and experience of God as life’s greatest goal.
Footnotes
[1] Scott R. Swain, The Trinity: An Introduction, (Wheaton, Ill, Crossways, 2020), p.20)
[2] Swain, p. 25
[3] This is clearly laid out by Paul in Ephesians 1:1-14, where salvation originates with the eternal will and purpose of the Father, (1:3-6) is accomplished by the redeeming work of the Son on the cross, (1:7-12) and applied to us by the “sealing” work of the Holy Spirit. (See Ephesians 1:12-14)
[4] Michael Reeves, https://www.desiringgod.org/articles/simply-divine
[5] Matthew Barrett, Divine Simplicity, [https://www.thegospelcoalition.org/essay/divine-simplicity/] Accessed online Feb 20, 2025.
[6] Swain, p. 29.
[7] Swain’s does not use the word “origin” or “originates” in the sense of a chronological beginning point. The Trinity means Son and Spirit are co-eternal with the Father, and so like the Father have no beginning and no end. Rather, he uses it in terms of source or fount. The Father is the eternal source of the Son’s life, for the Father “has life in himself” (John 5:26)