Everything in The Mission, The Power, and The Preparation has assumed a God worth knowing. This session asks the question those movements never paused to answer directly: who, exactly, is He?
“Can you find out the deep things of God? Can you find out the limit of the Almighty? It is higher than heaven — what can you do? Deeper than Sheol — what can you know?”
Can a doctrine be both completely true and only partially comprehensible?
That’s the honest starting posture for this session. Christians confess that God is three Persons and one God — Father, Son, and Holy Spirit — and the word most commonly used for that confession, “Trinity,” never actually appears in Scripture. That single fact makes some believers nervous. It shouldn’t. This session will make the case, directly from Scripture, that the doctrine is thoroughly biblical even though its name is not — and it will be honest about exactly where understanding runs out and worship has to begin instead.
Consider This
Before this session makes its case, notice your own starting point. If someone asked you right now to explain the Trinity in one sentence, what would you say — and how confident are you in that sentence?
Opening Prayer (Say this aloud!)
Father, the fact that You are ultimately beyond my full comprehension is unsettling, but it isn’t unsatisfying. I want to know everything You’ve revealed about Yourself, and I want the humility to be at peace with what You haven’t. Holy Spirit, teach me. In Jesus’ name, amen.
Start with the text every faithful Jew has recited twice daily for millennia:
“Listen, Israel: The Lord is our God, the Lord is one (אֶחָד)!”
Word Study
אֶחָד echad H259
“one” · Deuteronomy 6:4
Range. Echad is Hebrew’s ordinary word for the number one, appearing roughly 970 times across the Old Testament. Its range runs from simple arithmetic (“one man,” “one day”) to a specific compound sense: unity formed out of more than one part.
The sense here. The Shema’s confession that “the Lord is one” uses echad, not the Hebrew word for an indivisible singularity (yachid, used elsewhere for an only child — Genesis 22:2). That choice of word matters. The same echad describes marriage: “a man leaves his father and mother and unites with his wife, and they become a new family” (Genesis 2:24) — two distinct persons, described as echad, one. A husband and wife are genuinely two; Scripture calls their union echad anyway.
Why it carries the argument. This doesn’t prove the Trinity by itself — echad is used plenty of places for a plain, simple one, and this session won’t claim more precision than the word actually carries. What it shows is that Hebrew’s ordinary word for “one,” used by God to describe His own unity in the Shema, is fully compatible with — and elsewhere in the same book of the Torah, actually describes — a unity that contains real plurality. The Shema was never grammatically forced to mean “one” in the flattest possible sense.
Source. BDB, s.v. אֶחָד.
That compatibility becomes suggestive the moment you notice how God refers to Himself elsewhere in Genesis.
“Then God said, ‘Let us (נַֽעֲשֶׂה) make humankind in our image, after our likeness…’”
Word Study
אֱלֹהִים elohim H430
“Let us” · Genesis 1:26
Range. Elohim, God’s most common Old Testament name, is grammatically plural in form — the plural of eloah. It’s used well over two thousand times, and BDB notes it most frequently governs singular verbs and adjectives when referring to the one true God, a pattern grammarians call the “plural of majesty.”
The sense here. That caveat matters, and this session states it plainly rather than skip past it: the plural form of elohim alone doesn’t prove a triune God. A plural-of-majesty explanation is genuinely available, and honest scholarship acknowledges it. What tips the evidence further is what happens when elohim is paired with first-person-plural pronouns describing God’s own action — “let us make… in our image, after our likeness” (Genesis 1:26), “the man has become like one of us” (Genesis 3:22), “let us go down” (Genesis 11:7). A plural of majesty explains a plural noun. It doesn’t as easily explain God referring to Himself with plural pronouns while still, three verses later, being confessed as echad — one.
Why it carries the argument. Genesis doesn’t argue for a Trinity outright — the doctrine’s full shape only comes into focus once the New Testament identifies the plurality as Father, Son, and Spirit. But it plants something real: a text that describes the one true God, in His own words, using language too plural for simple singularity and too unified for simple multiplicity. Scripture’s own writers left that tension sitting in the text, unresolved, for well over a thousand years before the New Testament resolved it.
Source. BDB, s.v. אֱלֹהִים.
Illustration
The Old Testament’s clearest single hint may be the one hiding in plain sight inside the Shema itself. “The Lord is echad” — one — is the same word Genesis uses for a husband and wife becoming “one flesh” (Genesis 2:24): two real, distinct persons, genuinely called one. Rabbinic tradition has never fully explained why the text chose that particular word for God’s unity rather than the more absolute yachid. Long before any New Testament writer named Father, Son, and Spirit, the vocabulary for describing their unity was already sitting inside Israel’s own daily confession of faith.
Pause & Reflect
Does it surprise you that the Old Testament’s own vocabulary already had room for plurality-within-unity, centuries before the New Testament named who that plurality actually was?
Whatever the Old Testament left as suggestive tension, the New Testament resolves directly — beginning with the single scene where all three Persons appear together.
Illustration
“When Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him; and behold, a voice from heaven said, ‘This is my beloved Son, with whom I am well pleased’” (Matthew 3:16–17). In a single moment: the Son standing in the water, the Spirit visibly descending, the Father’s voice speaking from heaven. Not three gods taking turns. Not one God changing costumes. Three distinct, simultaneous, mutually addressing Persons at the same event — the Son being spoken to by the Father, the Spirit resting on the Son. Every Gospel writer records this scene (Matthew 3:16–17, Mark 1:10–11, Luke 3:21–22, John 1:32–34); it wasn’t a detail any of them thought to soften or omit.
The pattern repeats throughout the New Testament’s own vocabulary for God, most explicitly in the words Jesus Himself commanded His followers to use: “Go and make disciples of all nations, baptizing them in the name of the Father and the Son and the Holy Spirit” (Matthew 28:19). Notice the grammar carefully — name, singular, not names, plural — one name shared by three distinct Persons, named individually. Paul’s letters make the same move repeatedly, almost as a matter of course rather than a deliberate argument: “the grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all” (2 Corinthians 13:14); “there are varieties of gifts, but the same Spirit; and there are varieties of service, but the same Lord; and there are varieties of activities, but it is the same God who empowers them all” (1 Corinthians 12:4–6).
The clearest single verse for the claim that each Person is fully God, not a lesser or created being, is one the writer of Hebrews uses about the Son:
“The Son is the radiance of his glory and the representation (χαρακτὴρ τῆς ὑποστάσεως) of his essence, and he sustains all things by his powerful word.”
Word Study
ὑπόστασις hypostasis G5287
“essence” · Hebrews 1:3
Range. Hypostasis is a rich, technical Greek term: literally “that which stands under,” it came to mean the actual, underlying substance or reality of a thing — as opposed to its mere appearance. Outside this specific theological use, it also carries a sense of confident assurance (Hebrews 11:1’s “faith is the assurance [hypostasis] of things hoped for”).
The sense here. Hebrews pairs hypostasis with charaktēr — the precise image stamped by a die onto a coin, an exact impression rather than a rough resemblance. The Son isn’t described as resembling God’s essence from the outside. He’s described as its exact, stamped impression — sharing the identical underlying reality the word names.
Why it carries the argument. This is the very word later theologians borrowed to describe the “Persons” of the Trinity — three hypostaseis, one ousia (essence). Hebrews 1:3 is the New Testament seed of that later technical vocabulary: whatever the Father’s essence actually is, Hebrews says the Son is its exact representation, not an inferior copy. That single verse is the direct textual answer to the ancient error — Arianism — that this session’s next section names by name.
Source. Thayer’s Greek Lexicon, s.v. ὑπόστασις.
Pause & Reflect
Hebrews 1:3 says the Son is the “exact representation” of God’s essence, not merely a reflection of it. What difference does that distinction make for how you think about Jesus?
This isn’t merely a doctrine to confess correctly and set aside — it shapes the ordinary mechanics of a believer’s own prayer life, the territory Session 14 already walked through in detail. “Through him [Christ] we both have access in one Spirit to the Father” (Ephesians 2:18) describes prayer itself as a genuinely Trinitarian act: access secured by the Son, granted through the Spirit, directed to the Father. When you pray “in Jesus’ name,” you’re not invoking a password. You’re standing inside the actual relational structure Ephesians 2:18 describes — one Spirit, one access, one Father, made available through one Son. The doctrine this session is working to state precisely is the same doctrine you’ve likely already been living out, less precisely, every time you’ve prayed.
Historic, orthodox Christianity summarizes everything the Old and New Testaments together reveal about God’s nature in three simple statements, and every significant historical error about the Trinity has come from denying exactly one of them.
God is three Persons. Each Person is fully God. There is one God. Hold all three simultaneously, deny none of them, and you have the doctrine the church has confessed since its earliest centuries — formally clarified, though not invented, at the Council of Nicaea in 325 A.D., convened by the emperor Constantine to settle a controversy a presbyter named Arius had ignited seven years earlier. Arius taught that the Son was a created being, exalted but not eternal — a direct denial of the second statement above. The council’s response, later completed at a second council in Constantinople in 381 A.D., produced the Nicene Creed: language affirming that Jesus is “true God from true God… of one essence with the Father.” The council didn’t invent the doctrine of the Trinity. It clarified, under real theological pressure, language the church needed in order to keep saying accurately what Scripture had already revealed.
Illustration
At Nicaea, the debate wasn’t academic. Arius and his opponents — most famously the young deacon Athanasius, who would spend much of the rest of his life defending the council’s conclusion against repeated attempts to reverse it — were arguing about whether the Jesus Christians worshiped and prayed to was actually, fully God, or merely God’s first and greatest creation. Athanasius’s own later summary of what was at stake became a well-known theological principle: only a fully divine Savior could actually save. A created being, however exalted, could represent humanity to God, but could not accomplish what only God Himself can do. The stakes of getting this doctrine right were never merely intellectual.
The Shield of the Trinity
The Shield of the Trinity (Latin Scutum Fidei) — a diagram used in Western Christian teaching since at least the 12th century. Unlike the analogies below, it doesn’t compare God to anything outside Himself. It states the doctrine’s own relations directly: each Person is God, and no Person is either of the other two.
Three historic errors, each denying one leg of the three-legged truth above, are worth naming specifically:
Denying God is three Persons produces Modalism — the claim that God is a single Person who merely appears in different “modes” (Father, then Son, then Spirit) at different times, the way an actor plays different roles. This fails the baptism scene directly: Modalism can’t explain Father, Son, and Spirit being simultaneously present and distinct at the Jordan.
Denying each Person is fully God produces Arianism — the ancient error named above, still alive today in groups that teach Jesus is a created, lesser being rather than fully God. Hebrews 1:3’s “exact representation of his essence” is Scripture’s own direct answer to this error.
Denying there is one God produces Tritheism — treating Father, Son, and Spirit as three separate gods rather than one God in three Persons. This is historically the rarest of the three errors, but it’s the one popular analogies (see below) most often accidentally teach.
Humans reach for analogies to make hard ideas graspable. Every common analogy for the Trinity fails, and noticing exactly how each one fails is itself a useful way to understand the doctrine more precisely.
Water can be solid, liquid, or gas — one substance, three forms. But a single water molecule is only ever one of those forms at a time, never all three simultaneously the way Father, Son, and Spirit are simultaneously, eternally distinct. This analogy quietly teaches Modalism. A triangle has three distinct sides forming one shape. But any single side, alone, is just a line — not a triangle. This analogy quietly teaches Arianism: each “Person” alone isn’t fully what the whole is. Three separate individuals — three close friends, say — are three distinct persons. But three friends are three separate beings, not one. This analogy quietly teaches Tritheism. Every analogy reaches for something in ordinary experience and comes up short, because nothing in ordinary experience is three fully distinct, co-equal, co-eternal Persons sharing one undivided essence. That’s not a flaw in the teachers who use these analogies. It’s a genuine limit of finite comparison applied to an infinite, unique reality.
Another Voice
“No man can fully explain the Trinity, though in every age scholars have propounded theories and advanced hypotheses to explore this mysterious Biblical teaching… Perhaps the chief reason for this is that the Trinity is a-logical, or beyond logic. It, therefore, cannot be made subject to human reason or logic.”
— Walter Martin, Essential Christianity (1975)
That’s not an excuse to stop thinking carefully — this entire session has been an exercise in thinking carefully. It’s a recognition that some true things are genuinely bigger than the human mind’s native categories, the way a child can trust a parent’s love completely without comprehending everything about how that love works. “The secret things belong to the Lord our God, but the things that are revealed belong to us” (Deuteronomy 29:29). Scripture reveals enough about the Trinity to be confessed, worshiped, and trusted. It doesn’t reveal enough to be fully diagrammed.
Paul himself, writing to a church he’d personally taught for well over a year, admits the same limit about knowing God generally: “now we see in a mirror dimly, but then face to face. Now I know in part; then I shall know fully, even as I have been fully known” (1 Corinthians 13:12). If the apostle who wrote a third of the New Testament was content to know in part, a modern reader working through a discipleship curriculum can hold the same posture without embarrassment. Partial knowledge of an infinite God, held with confidence rather than anxiety, is not a failure of faith. It’s the appropriate size of a finite mind’s grasp on the God who made it.
This is a fair, commonly raised objection, and it deserves a real answer rather than a defensive dismissal. Ancient religions did have groupings of three gods — Egyptian, Babylonian, and later Hindu triads are the examples most often raised. If Christianity’s Trinity is just another version of the same instinct toward divine threes, the doctrine looks more like inherited mythology than revealed truth.
The comparison doesn’t hold up under any real scrutiny, for a specific, structural reason. Pagan “trinities” are collections of separate gods — genuinely three distinct beings, each with independent origin, will, and existence, sometimes ranked in a hierarchy, sometimes simply grouped by association or family. That’s Tritheism, precisely the error this session’s Common Errors section already named and rejected. The Christian doctrine claims something structurally different and, as far as comparative religious history shows, essentially unique: not three gods, but three Persons who are co-equal, co-eternal, and share a single, undivided essence — one God, not three gods cooperating. No pagan triad in the ancient world made that specific claim, because the claim itself only makes coherent sense within a framework, like Israel’s, that had already firmly established there is exactly one God to begin with. Trinitarian theology didn’t emerge from polytheism gradually softening into unity. It emerged from the strictest monotheism in the ancient world — the Shema itself — being pressed by direct New Testament revelation to include real plurality it had never previously named.
This is a guided practice of worship addressed specifically to each Person of the Trinity in turn, then together — not because they can be worshiped separately (they cannot; there is one God), but because addressing each by name deepens what “worshiping the Trinity” actually means beyond an abstract phrase.
Find a quiet space. Pray each section aloud, slowly, pausing between them.
To the Father: “Father, I worship You as the source of all things, the One from whom every good gift comes. Thank You for loving me before I ever loved You. I receive Your Fatherhood over my life today.”
To the Son: “Jesus, I worship You as fully God and fully man, the exact representation of the Father’s own essence, who gave Yourself for me. Thank You for making the Father known and for making a way for me to know Him. I receive Your lordship over my life today.”
To the Holy Spirit: “Holy Spirit, I worship You as fully God, my Helper and Guide, who dwells in me and teaches me all things. Thank You for never leaving me alone. I receive Your presence and leadership over my life today.”
To the Triune God, together: “Father, Son, and Spirit — three Persons, one God, beyond my full comprehension and worthy of my complete trust. I can’t fully explain You. I can fully worship You. Amen.”
Big Ideas
Kingdom Principle
Not fully comprehending God is not the same as not being able to trust Him. Confession and worship don’t require complete comprehension — they require accurate, humble trust in what has actually been revealed.
Closing Prayer (Say this aloud!)
Father, Son, and Spirit — one perfect God in three Persons. The math doesn’t resolve, yet You are exactly who You are, not what I imagine or wish You to be. Expand my capacity to understand what You’ve revealed, and my willingness to be amazed by what You haven’t. I can only bow in worship at how great You truly are. In Jesus’ name, amen.
Go Deeper
Accessible
The Bible Project’s video series on the Trinity (available on YouTube), or Kenneth Boa’s Unraveling the Big Questions About God. Both are aimed at a general audience without sacrificing theological accuracy.
Substantial
Walter Martin, The Kingdom of the Cults (1965, frequently revised and updated since). The standard evangelical reference for how the historic errors this session named show up in specific present-day groups and movements.
Academic
J. N. D. Kelly, Early Christian Doctrines, chapters on the fourth-century Trinitarian controversies. A rigorous historical treatment of exactly how the church arrived at Nicene and post-Nicene Trinitarian language, and why it mattered as much as it did.
Day 1 Read Job 11:7–8 slowly. How must a heart be positioned to study a doctrine this far beyond full comprehension?
Day 2 Read Deuteronomy 6:4–5 aloud, then Genesis 2:24. Notice the shared word, echad. Let both texts sit together without rushing to resolve the tension.
Day 3 Read Matthew 3:16–17 and picture the scene. All three Persons, present and distinct, at one moment in history. What does this scene rule out about how you’d previously pictured God?
Day 4 Read Hebrews 1:1–3. “The exact representation of his essence.” Sit with what this claims about who Jesus actually is.
Day 5 Reread this session’s three failed analogies (water, triangle, three friends). Which analogy, if any, has quietly shaped your own picture of God without your realizing it?
Day 6 Revisit this session’s Experience. Did addressing each Person by name, in turn, change how “worshiping God” felt compared to your ordinary prayer?
Tell one trusted person this week one thing about the Trinity you now hold with more confidence, and one thing you’re still honestly wrestling to understand.
If something in this session stuck with you, confused you, or hit harder than you expected, I’d genuinely like to hear it — email me.
Kingdom Essentials · Session 23 · Argument Map
The Trinity
“Can God be three Persons and one God — genuinely, at the same time?”
Hebrew’s own word for God’s “oneness” already had room for real plurality, and God’s own plural self-reference plants a tension the Old Testament leaves sitting there, unresolved, for over a thousand years.
At the Jordan, Father, Son, and Spirit appear simultaneously distinct — not three gods taking turns, not one God changing costumes. One name, singular, shared by three Persons named individually.
Three Persons, each fully God, one God — hold all three and deny none. Deny any one leg and you get Modalism, Arianism, or Tritheism.
Every common analogy for the Trinity quietly teaches one of the three historic errors. Scripture reveals enough to be confessed and worshiped. It doesn’t reveal enough to be fully diagrammed.
“The secret things belong to the Lord our God.” Not fully comprehending God is not the same as not being able to trust Him.
So Now
The Old Testament’s own vocabulary for God’s oneness already had room for what the New Testament would go on to name.
The Son is the exact representation of the Father’s essence — not an inferior copy, not a created being.
Baptizing in the name — singular — of the Father, Son, and Holy Spirit: three Persons, individually named, sharing one name.
Scripture reveals enough about the Trinity to be confessed and worshiped — not enough to be fully explained.
Kingdom Principle
Not fully comprehending God is not the same as not being able to trust Him. Confession and worship don’t require complete comprehension — they require accurate, humble trust in what has actually been revealed.
Next · Session 24, The Unknowable God. You’ve confessed who God is in His triune fullness. Session 24 turns to a related, equally humbling question: what it means that this same God is simultaneously knowable and, in real ways, beyond knowing.
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