Defending the Trinity

What you'll learn

Diagnose an objection to the Trinity by identifying which of the three biblical truths it denies, and answer it from Scripture
Answer the charges that the Trinity is a logical contradiction and that it was invented at Nicaea, without relying on analogies
Respond to the main texts used against the Trinity (Deut 6:4, John 17:3 and Acts 2:38) by reading them in context

Why the Trinity is attacked, and where to start

The Trinity answers the question 'Who is God?' Get God wrong and you get worship, salvation and prayer wrong. Jehovah's Witnesses, Muslims, Oneness Pentecostals and Latter-day Saints all reject the historic doctrine, so you will meet these objections often.

You studied the doctrine in Know Your Faith, Lesson 3; this lesson is about defending it. Have the definition ready: within the one being of God there eternally exist three coequal, coeternal persons: the Father, the Son and the Holy Spirit. It is not a contradiction. A contradiction would be 'one being and three beings' or 'one person and three persons'. God is one in one sense (being, what he is) and three in a different sense (persons, who he is). That is a mystery, because we cannot fully picture it, but it is not nonsense.

Why does the lesson say the Trinity is not 'theological trivia'? Explain in your own words.Show answer

The Trinity answers the question 'Who is God?', so it is not a side issue. If we get God wrong, we also get worship, salvation and prayer wrong. Several groups we will meet, such as Jehovah's Witnesses, Muslims, Oneness Pentecostals and Latter-day Saints, reject it, so we will face these objections often.

Answers 'Who is God?'
Affects worship, salvation, prayer
Many groups reject it

What is the difference between a mystery and a contradiction, as applied to the Trinity?Show answer

A contradiction would say God is one and three in the same sense, such as one being and three beings, or one person and three persons. The Trinity says God is one in one sense (being, what he is) and three in a different sense (persons, who he is). We cannot fully picture this, so it is a mystery, but it is not nonsense.

Contradiction = same sense
One in being, three in person
Mystery is not nonsense

Recap: three biblical truths

In Know Your Faith you met James White's approach from The Forgotten Trinity (1998): show three truths the Bible plainly teaches. The doctrine of the Trinity is simply what you get when you refuse to deny any of them. Whatever the objection, come back to these truths and their texts.

Truth 1: There is only one true God (Deut 6:4; Isa 43:10; 44:6-8; 45:5; 1 Cor 8:4-6).

Truth 2: There are three distinct persons. At Jesus' baptism the Son is in the water, the Spirit descends and the Father speaks from heaven (Matt 3:16-17). The Son prays to the Father (John 17), the Father sends the Son (John 3:17), and the Son and Father send 'another Helper', the Spirit (John 14:16, 26; 15:26). A 'person' means a distinct 'who', with self-awareness and relationships, not a separate being.

Truth 3: Each person is fully God. The Father (John 6:27), the Son (John 1:1; 20:28; Titus 2:13; Heb 1:8) and the Spirit, since lying to him is lying to God (Acts 5:3-4). Matthew 28:19 places all three under one 'name'.

Summarise James White's three biblical truths, and explain how the doctrine of the Trinity relates to them.Show answer

The Bible teaches that there is only one true God, that there are three distinct divine persons (Father, Son and Spirit), and that each person is fully and equally God. The doctrine of the Trinity is simply what you get when you refuse to deny any of these three truths. It starts from what Scripture plainly says rather than from a philosophical definition.

Only one true God
Three distinct persons
Each fully God
Refuse to deny any

Which texts show that the Father, Son and Spirit are distinct persons rather than one person in three masks, and how?Show answer

At Jesus' baptism the Son is in the water, the Spirit descends and the Father speaks from heaven, all at once (Matt 3:16-17). The Son prays to the Father (John 17), the Father sends the Son (John 3:17), and the Son and Father send 'another Helper', the Spirit (John 14:16, 26; 15:26). These relationships only make sense between distinct 'whos', each with self-awareness, not one person changing roles.

Baptism scene (Matt 3:16-17)
Son prays to Father
Father sends Son; Spirit is 'another'
Person = distinct 'who'

Diagnose first: which truth is being denied?

Every objection to the Trinity drops one of the three truths. You learned the classic errors in Know Your Faith, Lesson 3. In conversation, first ask yourself: 'Which truth is this person dropping?' Then go to the texts for that truth.

Oneness Pentecostals drop truth 2. Their view is modalism: one person who reveals himself in three modes or roles. Answer with the real relationship between Father and Son before the incarnation: the Word was 'with God' (John 1:1), and the Father loved the Son and shared his glory before the world began (John 17:5, 24).
Jehovah's Witnesses drop truth 3 for the Son. Their view is closest to historic Arianism, which made the Son a created, lesser 'god' (and historically the Spirit a creature too); the Watchtower adds that the holy spirit is an impersonal active force. Answer with John 1:3 (all things were made through him, so he is not one of the made things), the worship given to the Son (Heb 1:6; Rev 5:13-14) and the Spirit's personal actions (Acts 5:3-4; 13:2).
Latter-day Saints drop truth 1. They teach that the Father, the Son and the Holy Ghost are separate beings, the Father and Son having bodies of flesh and bones (D&C 130:22). That is a form of tritheism. Answer with Deuteronomy 6:4 and Isaiah 44:6-8, where God knows of no other God.
Muslims usually think we have dropped truth 1, while they deny truths 2 and 3 (Quran 4:171; 5:73). Some have heard that the Trinity includes Mary (Quran 5:116 pictures Jesus being asked whether he told people to take him and his mother as gods). First correct the misunderstanding: we do not believe in three gods, and Mary is not part of the Godhead.
Well-meaning Christians sometimes slip into partialism, as if each person were a third of God. But the whole fullness of deity dwells in Christ (Col 2:9).

What is the difference between modalism and Arianism, and which of the three truths does each deny?Show answer

Modalism (today, Oneness Pentecostalism) denies the second truth: it says God is one person who shows himself in three modes or roles, so it cannot explain the Son praying to the Father or the Father loving the Son before the world began (John 17:5, 24). Arianism (whose closest modern parallel is the Watchtower) denies the third truth for the Son: it makes him a created, lesser 'god'. That collides with John 1:3 and with the worship given to the Son (Heb 1:6; Rev 5:13-14).

Modalism denies distinct persons
Arianism denies Son's full deity
John 17:5, 24 vs modalism
John 1:3 vs Arianism

Which of the three truths do Latter-day Saints drop, and what do many Muslims wrongly think Christians believe? How would you answer each?Show answer

Latter-day Saints drop truth 1: they teach three separate divine beings (D&C 130:22), a form of tritheism, which the Shema (Deut 6:4) and Isaiah 43:10 and 44:6-8 rule out. Many Muslims think Christians believe in three gods, and some think the Trinity includes Mary (compare Quran 5:116). The first step is to correct the misunderstanding: we confess one God, and Mary is not part of the Godhead.

LDS drop truth 1 (three beings)
Answer: Deut 6:4; Isa 44:6-8
Muslims think we believe in three gods
Correct the misunderstanding first

Answering 'It's illogical', without leaning on analogies

When someone says 'The Trinity is illogical', ask them to state the contradiction. Usually they say 'one God who is three Gods', which is not what we believe. A real contradiction affirms and denies the same thing in the same sense. We say one in being, three in person. Then ask which of the three truths they think the Bible does not teach. That moves the discussion from philosophy to texts, which is where you want it.

Do not stake your case on an analogy. Most popular illustrations teach a heresy (hence Lutheran Satire's video 'St. Patrick's Bad Analogies'). Water, ice and steam is modalism. The egg and the shamrock are partialism: each part is only a piece of the whole. The sun, its light and its heat tends towards Arianism, since light and heat are products of the sun, not equal to it. A trained opponent will happily attack your analogy instead of your texts.

Admit instead that God is unique: 'To whom then will you liken God?' (Isa 40:18). Being unlike anything in creation does not make a belief incoherent; it is what we should expect of the Creator.

Pick one popular Trinity analogy and explain which heresy it accidentally teaches.Show answer

Water, ice and steam is modalism, because it pictures one substance appearing in three states rather than three persons existing together. The egg and the shamrock are partialism, since each part is only a piece of the whole. The sun, its light and its heat tends towards Arianism, because light and heat are products of the sun, not equal to it.

Water/ice/steam = modalism
Egg/shamrock = partialism
Sun/light/heat = Arianism

Put the short definition of the Trinity into one or two sentences you could say to a friend, then explain how you would move the conversation forward.Show answer

Within the one being of God there eternally exist three coequal, coeternal persons: the Father, the Son and the Holy Spirit. First ask the person to state the contradiction they see, since they usually say 'one God who is three Gods', which is not what we believe. Then ask which of the three truths they think the Bible does not teach, which moves the discussion from philosophy to texts.

One being, three persons
Coequal and coeternal
Ask them to state the contradiction
Move to the texts

Answering 'It was invented at Nicaea'

Recall the history (Know Your Faith, Lesson 3; The Story of the Church, Lesson 2). In the early 300s Arius taught that the Son was the first and highest creature: 'there was a time when he was not'. The Council of Nicaea (AD 325) answered that the Son is 'of one substance' (homoousios) with the Father, 'begotten, not made'. The Council of Constantinople (AD 381) confessed the Spirit as 'the Lord, the giver of life', who proceeds from the Father and 'with the Father and the Son together is worshipped and glorified'.

Your answer has three parts. Councils do not invent doctrines; they respond to denials of what churches already believed. Before 325 Christians were already baptising in the triune name (Matt 28:19; Didache 7) and worshipping Jesus: Pliny the Younger's letter to Trajan, around AD 112, reports Christians singing hymns 'to Christ as to a god'. And the final test is Scripture, not a council: Nicaea built a fence around the truth when someone tried to move it. Reformed confessions (WCF 2.3; LBCF 1689, 2.3) affirm the same Nicene faith.

What did Arius teach, and how did the Council of Nicaea answer him?Show answer

Arius taught that the Son was the first and highest creature, so that 'there was a time when he was not'. Nicaea (AD 325) answered that the Son is 'of one substance' (homoousios) with the Father, 'begotten, not made'. Constantinople (AD 381) later confessed the Spirit as 'the Lord, the giver of life', worshipped and glorified with the Father and the Son.

Arius: Son a creature
Nicaea: homoousios
Begotten, not made
381: Spirit worshipped

How would you answer someone who says, 'The Trinity was invented at Nicaea'?Show answer

Councils do not invent doctrines; they respond to denials of what churches already believed and practised. Christians were baptising in the triune name and worshipping Jesus long before 325, as Pliny the Younger's letter to Trajan (around AD 112) shows when it reports Christians singing hymns 'to Christ as to a god'. Nicaea built a fence around the truth when Arius tried to move it.

Councils respond, not invent
Worship of Jesus before 325
Pliny's letter c. AD 112
Fence around the truth

Answering the texts used against the Trinity

Opponents have favourite verses. Do not avoid them; read them in context, and show that the Trinity is what you get when you hold all the texts together.

Deuteronomy 6:4 ('the LORD is one'). Agree warmly: that is truth 1. But the verse says there is one LORD; it does not say God is one person. Paul keeps the Shema and places Jesus within it: 'one God, the Father... and one Lord, Jesus Christ, through whom are all things' (1 Cor 8:6). He uses the Shema's own words, 'God' and 'Lord', and gives Jesus the role of Creator.

John 17:3 ('the only true God'). We agree the Father is the only true God. The phrase contrasts the living God with false gods, not the Father with the Son, who in the same prayer speaks of sharing the Father's glory before the world existed (17:5).

Acts 2:38 ('in the name of Jesus Christ'). Oneness believers say this replaces Matthew 28:19. But Luke's phrase marks out Christian baptism, done on Jesus' authority, from John's baptism (compare Acts 19:3-5). It does not cancel Jesus' own command. Texts such as 'the Father is greater than I' (John 14:28) concern the Son's humanity and humble role; the next lesson handles them.

How would you answer someone who uses Deuteronomy 6:4 against the Trinity?Show answer

Agree warmly that there is one God, because that is truth 1 and Christians are monotheists. But the verse says there is one LORD; it does not say God is one person. The New Testament keeps the Shema and places Jesus within it: 1 Corinthians 8:6 speaks of 'one God, the Father' and 'one Lord, Jesus Christ, through whom are all things', using the Shema's own words and giving Jesus the role of Creator.

Agree: one God
Shema does not say one person
1 Cor 8:6 places Jesus within it
Jesus as Creator

A Oneness believer says Acts 2:38 shows the apostles replaced Matthew 28:19 with 'in the name of Jesus'. How would you respond?Show answer

Luke's phrase marks out Christian baptism, done on Jesus' authority, from John's baptism, as Acts 19:3-5 shows. It is not a rival formula that cancels Jesus' own command to baptise in the one name of the Father, the Son and the Holy Spirit (Matt 28:19). Reading the texts together, rather than setting them against each other, supports the Trinity.

Acts 2:38 marks Christian baptism by Jesus' authority
Compare Acts 19:3-5
Does not cancel Matt 28:19
Hold texts together

Why it is worth the effort

Remember why this matters. Only a triune God can be love in himself before creation (1 John 4:8; John 17:24). A single-person God needs a creation to have someone to love; the triune God shares his overflowing love with us freely. We defend the Trinity not to win a word game but to introduce people to the God who is really there. The Trinity is not just defensible; it is beautiful.

Why does the lesson call the Trinity beautiful, not just defensible?Show answer

Only a triune God can be love in himself before creation (1 John 4:8; John 17:24). A single-person God would need a creation to have someone to love. The triune God does not need us, but freely shares his overflowing love with us.

God is love eternally
Love within the persons
Single-person God needs creation
Love shared freely

In their own words

“There is one God, one in person, not three. In the UPCI's words, 'This one true God has revealed Himself as Father; through His Son, in redemption; and as the Holy Spirit, by emanation.' Jesus is the name of that one God revealed in flesh.” (UPCI Articles of Faith, 'The One True God'; David K. Bernard, The Oneness of God (1983))

“Jesus is 'a god', the first creation of Jehovah, and the holy spirit is God's active force, not a person.” (New World Translation, John 1:1; Watchtower booklet Should You Believe in the Trinity? (1989))

“Say not 'Three'; God is only one God, far exalted above having a son.” (Quran 4:171; see also 5:73, 112:1-4)

Key texts

Deuteronomy 6:4: The Shema establishes truth 1. Agree with your opponent strongly here: Christians are monotheists.
Isaiah 44:6-8: God knows of no other God. This rules out the Watchtower's 'mighty god' Jesus as a second, lesser deity, since any other true god would contradict Yahweh's own words.
Matthew 28:19: One 'name' (singular) shared by three persons distinguished by the article: the Father, the Son and the Holy Spirit.
John 1:1-3: The Word was with God (distinct person) and was God (same divine nature), and is uncreated because all things came into being through him.
John 17:5, 24: The Son shared glory with the Father and was loved by him before the world existed. This refutes modalism, which has no real relationship before the incarnation.
Acts 5:3-4: Lying to the Holy Spirit is lying to God, showing the Spirit is both personal and divine.
1 Corinthians 8:6: Paul uses the Shema's own words, 'one God' and 'one Lord', and places Jesus within them as the one through whom all things exist. Use it when someone sets Deuteronomy 6:4 against the Trinity.

Objections and answers

Try answering each one yourself before you open the response.

“The word 'Trinity' is not even in the Bible. You are believing a man-made doctrine.”Show a response

That is true of the word, but a word is a label for a teaching, not the teaching itself. 'Monotheism' and 'Bible' are not in the Bible either, yet you believe in one God and in a collection of sacred books. The question is whether the content the word summarises is biblical. So let's test it: does the Bible teach there is one God? Does it present the Father, Son and Spirit as distinct persons? Does it call each of them God or give each divine attributes? If all three are biblical, then the doctrine is biblical, whatever we call it. Which of those three do you think the Bible does not teach? I'm happy to look at the texts together.

“One plus one plus one equals three, not one. The Trinity is a mathematical contradiction.”Show a response

It would be a contradiction if we said God is one being and three beings, or one person and three persons. We say neither. We say God is one in being and three in person. Those are different categories, just as you are one human being with both a body and a mind. (That is not a picture of the Trinity, only a reminder that 'one' and 'more than one' can apply in different categories.) If you want a mathematical picture, the Trinity is not 1+1+1=1; it is closer to 1x1x1=1, since each person is fully God, not a fraction. But the real question is not arithmetic; it is revelation. We only know what God is like because he has told us, and he has told us there is one God who exists as Father, Son and Spirit.

“The Trinity was invented by Constantine and the Council of Nicaea in 325.”Show a response

Constantine called the council, but he did not dictate its theology, and the bishops were responding to Arius, not inventing a new idea. Before 325, Christians were already baptising in the name of the Father, Son and Spirit (Matt 28:19; Didache 7), worshipping Jesus (Phil 2:10-11; Rev 5), and calling him God (John 20:28). Ignatius of Antioch, around AD 110, calls Jesus 'our God' in his letters. Tertullian used the Latin word trinitas in the early 200s. Nicaea clarified an existing faith under attack. Also, if Constantine wanted to impose the Trinity, he did a poor job: he later favoured Arian bishops, and the debate continued for decades.

“If Jesus is God, then God died on the cross. Who was running the universe for three days?”Show a response

This objection assumes the Son is the only divine person, which is modalism, not the Trinity. The Father and the Spirit did not cease to be God at Calvary. Also, in his incarnation the Son took a real human nature. Death is the separation of soul from body, and that is what happened to Jesus' human nature. The divine nature cannot cease to exist. So the person of the Son truly died in his humanity, which is why the Bible can say the Lord of glory was crucified (1 Cor 2:8), while the divine life of the Godhead continued unbroken. Colossians 1:17 says in him all things hold together, and that did not pause.

“Jesus himself prayed to the Father as 'the only true God' (John 17:3). How much clearer can it get? The Father alone is God.”Show a response

That verse matters, and we fully agree the Father is the only true God; that is truth 1. The question is whether 'only' shuts the Son out. In the same prayer Jesus speaks of the glory he had with the Father before the world existed (John 17:5), which no creature could say. 'Only true God' contrasts the living God with false gods, not the Father with the Son. Compare Jude 4, which calls Jesus Christ 'our only Master and Lord'. No one thinks that means the Father is not Lord. The same John who records this prayer opens his Gospel by saying the Word was God and all things were made through him (John 1:1-3). The Trinity is what you get when you hold both texts together instead of setting them against each other.

“As a Muslim, I find this simple: God is one. Christians worship three gods and then call it a mystery to avoid admitting it.”Show a response

I appreciate your zeal for God's oneness, and I share it. If Christians worshipped three gods, you would be right to object, and so would the Bible: 'The LORD our God, the LORD is one' (Deut 6:4). Tritheism is a heresy the church has always rejected. What we confess is one God, one being, in whom there are three persons: the Father, the Son and the Spirit. We are not saying one and three in the same sense, which would be a contradiction. Could I show you why we believe this? It is not because we find it easy, but because the same Scriptures that insist God is one also show the Father, the Son and the Spirit as distinct persons who are each called God and receive worship that belongs to God alone.

Written task

A friend from your church tells you: 'I've always believed in the Trinity, but honestly I can't explain it. When my Muslim workmate asked me, I said it's like water, ice and steam.' Write a 250-350 word reply to your friend that gently corrects the analogy, explains the three biblical truths with at least one text each, and gives them a one-sentence definition they could use with their workmate next time.

Hand this in to Mr Scott. He will look for:

Identifies the water analogy as modalism and explains why that is a problem in plain language
States all three biblical truths accurately with a relevant text for each
Gives a clear one-sentence definition distinguishing 'being' from 'person'
Anticipates the Muslim concern about tritheism and affirms monotheism
Tone is warm and encouraging, not condescending