[all passages RSV unless otherwise noted]
1. The Unity of God and Monotheism
Deuteronomy 6:4 Hear, O Israel: The LORD our God is one LORD; (cf. Mk 12:29; 1 Cor 8:6; Eph 4:5-6; 1 Tim 2:5; Jas 2:19)
Deuteronomy 32:39 …there is no god beside me.…
Isaiah 37:20 …thou alone art the LORD. (cf. 37:16)
Isaiah 43:10 …Before me no god was formed, nor shall there be any after me.
Isaiah 44:8 …Is there a God besides me? There is no Rock; I know not any. (cf. 44:6; 45:5-6, 21-22; 46:9; Mal 2:10)
1 Corinthians 8:4 Hence, 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.”
Polytheism Condemned Furthermore, there is no such thing as a “Big God and a little god” scenario in Scripture, as Jehovah’s Witnesses, Mormons, and other heretics maintain. Polytheism is condemned as vigorously as monotheism is proclaimed. Satan is called “the god of this world” in 2 Corinthians 4:4, but this is to be understood as a “god” not in nature or essence, but only in the sense that people idolatrously worship it, him, or her, as we also see in the following passages:
2 Kings 17:35 …You shall not fear other gods or bow yourselves to them or serve them or sacrifice to them;
Isaiah 37:19 …for they were no gods, but the work of men’s hands, wood and stone.…
1 Corinthians 8:5-6 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,…
Galatians 4:8 Formerly, when you did not know God, you were in bondage to beings that by nature are no gods; (cf. Is 44:10, 15, 17; 46:6)
2. 40 Passages with All Three Divine Persons
Isaiah 42:1 Behold my servant, whom I uphold, my chosen, in whom my soul delights; I have put my Spirit upon him, he will bring forth justice to the nations.
Isaiah 61:1 The Spirit of the Lord GOD is upon me,… (cf. 61:2; Jesus applies this to Himself in Lk 4:16-30)
Matthew 28:19 Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit,
Luke 1:35 And the angel said to her, “The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born will be called holy, the Son of God.”
Luke 3:21-22 …when Jesus also had been baptized and was praying, the heaven was opened,  and the Holy Spirit descended upon him in bodily form, as a dove, and a voice came from heaven, “Thou art my beloved Son; with thee I am well pleased.” (cf. Mt 3:13-17)
John 14:16 And I will pray the Father, and he will give you another Counselor, to be with you for ever,
John 14:26 But the Counselor, the Holy Spirit, whom the Father will send in my name, he will teach you all things, and bring to your remembrance all that I have said to you.
John 15:26 But when the Counselor comes, whom I shall send to you from the Father, even the Spirit of truth, who proceeds from the Father, he will bear witness to me;
John 20:21-22 Jesus said to them again, “Peace be with you. As the Father has sent me, even so I send you.”  And when he had said this, he breathed on them, and said to them, “Receive the Holy Spirit.”
Acts 2:33 Being therefore exalted at the right hand of God, and having received from the Father the promise of the Holy Spirit, he has poured out this which you see and hear.
Acts 2:38-39 And Peter said to them, “Repent, and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit.  For the promise is to you and to your children and to all that are far off, every one whom the Lord our God calls to him.”
Acts 5:30-32 The God of our fathers raised Jesus whom you killed by hanging him on a tree.  God exalted him at his right hand as Leader and Savior, to give repentance to Israel and forgiveness of sins.  And we are witnesses to these things, and so is the Holy Spirit whom God has given to those who obey him.
Acts 7:55 But he, full of the Holy Spirit, gazed into heaven and saw the glory of God, and Jesus standing at the right hand of God;
Acts 10:38 how God anointed Jesus of Nazareth with the Holy Spirit and with power; how he went about doing good and healing all that were oppressed by the devil, for God was with him.
Acts 15:8, 11 And God who knows the heart bore witness to them, giving them the Holy Spirit just as he did to us;…  But we believe that we shall be saved through the grace of the Lord Jesus, just as they will.
Acts 20:28 Take heed to yourselves and to all the flock, in which the Holy Spirit has made you overseers, to care for the church of God which he obtained with the blood of his own Son.
Romans 8:9 But you are not in the flesh, you are in the Spirit, if in fact the Spirit of God dwells in you. Any one who does not have the Spirit of Christ does not belong to him.
Romans 8:11 If the Spirit of him who raised Jesus from the dead dwells in you, he who raised Christ Jesus from the dead will give life to your mortal bodies also through his Spirit which dwells in you.
Romans 8:16-17 it is the Spirit himself bearing witness with our spirit that we are children of God,  and if children, then heirs, heirs of God and fellow heirs with Christ,…
Romans 15:15-18 …the grace given me by God  to be a minister of Christ Jesus to the Gentiles in the priestly service of the gospel of God, so that the offering of the Gentiles may be acceptable, sanctified by the Holy Spirit.  In Christ Jesus, then, I have reason to be proud of my work for God.  For I will not venture to speak of anything except what Christ has wrought through me.…
Romans 15:30 I appeal to you, brethren, by our Lord Jesus Christ and by the love of the Spirit, to strive together with me in your prayers to God on my behalf,
1 Corinthians 2:2, 4-5 For I decided to know nothing among you except Jesus Christ and him crucified.…  …in demonstration of the Spirit and of power,  that your faith might not rest in the wisdom of men but in the power of God.
1 Corinthians 6:11 …justified in the name of the Lord Jesus Christ and in the Spirit of our God.
1 Corinthians 12:4-6 Now there are varieties of gifts, but the same Spirit;  and there are varieties of service, but the same Lord;  and there are varieties of working, but it is the same God who inspires them all in every one. (cf. Eph 4:4-6)
2 Corinthians 1:21-22 But it is God who establishes us with you in Christ, and has commissioned us;  he has put his seal upon us and given us his Spirit in our hearts as a guarantee.
2 Corinthians 3:3 …you are a letter from Christ delivered by us, written not with ink but with the Spirit of the living God.…
2 Corinthians 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.
Galatians 4:6 …God has sent the Spirit of his Son into our hearts.…
Ephesians 2:18 for through him we both have access in one Spirit to the Father.
Ephesians 2:19-22 …the household of God,  built upon the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone,  in whom the whole structure is joined together and grows into a holy temple in the Lord;  in whom you also are built into it for a dwelling place of God in the Spirit.
Ephesians 3:16-17 that according to the riches of his glory he may grant you to be strengthened with might through his Spirit in the inner man,  and that Christ may dwell in your hearts through faith.…
Ephesians 5:18, 20 …be filled with the Spirit,…  always and for everything giving thanks in the name of our Lord Jesus Christ to God the Father.
2 Thessalonians 2:13 But we are bound to give thanks to God always for you, brethren beloved by the Lord, because God chose you from the beginning to be saved, through sanctification by the Spirit and belief in the truth.
Titus 3:5-6 he saved us, not because of deeds done by us in righteousness, but in virtue of his own mercy, by the washing of regeneration and renewal in the Holy Spirit,  which he poured out upon us richly through Jesus Christ our Savior,
Hebrews 9:14 how much more shall the blood of Christ, who through the eternal Spirit offered himself without blemish to God, purify your conscience from dead works to serve the living God.
Hebrews 10:29 How much worse punishment do you think will be deserved by the man who has spurned the Son of God, and profaned the blood of the covenant by which he was sanctified, and outraged the Spirit of grace?
1 Peter 1:2 chosen and destined by God the Father and sanctified by the Spirit for obedience to Jesus Christ and for sprinkling with his blood.…
1 John 3:23-24 And this is his commandment, that we should believe in the name of his Son Jesus Christ and love one another, just as he has commanded us.  All who keep his commandments abide in him, and he in them. And by this we know that he abides in us, by the Spirit which he has given us.
1 John 4:2 By this you know the Spirit of God: every spirit which confesses that Jesus Christ has come in the flesh is of God,
Jude 1:20-21 …pray in the Holy Spirit;  keep yourselves in the love of God; wait for the mercy of our Lord Jesus Christ unto eternal life.
3. The Holy Spirit: 40 Personal Attributes
1) Helps: Jn 14:16, 26; 15:26; 16:7; Rom 8:26; 1 Jn 2:1.
2) Glorifies: Jn 16:13-14.
3) Can be Known: Jn 14:17.
4) Gives Abilities: Acts 2:4; 1 Cor 12:7-11.
5) Referred to as “He”: Jn 14:26; 15:26; 16:7-8, 13.
6) Loves: Rom 15:30.
7) Guides: Jn 16:13.
8) Comforts: Jn 14:26; 15:26; 16:7; Acts 9:31.
9) Teaches: Lk 12:12; Jn 14:26.
10) Reminds: Jn 14:26.
11) Bears Witness: Jn 15:26; Acts 5:32; Rom 8:16.
12) Has Impulses: Jn 16:13.
13) Hears: Jn 16:13.
14) Leads: Mt 4:1; Acts 8:39; Rom 8:14.
15) Pleads: Rom 8:26-27.
16) Longs (Yearns): Jas 4:5.
17) Wills: 1 Cor 12:11.
18) Thinks: Acts 15:25, 28.
19) Sends: Acts 13:4.
20) Dispatches: Acts 10:20.
21) Impels: Mk 1:12.
22) Speaks: Jn 16:13-15; Acts 8:29; 10:19; 11:12; 13:2.
23) Forbids: Acts 16:6-7.
24) Appoints: Acts 20:28.
25) Reveals: Lk 2:26; 1 Cor 2:10.
26) Calls to Ministry: Acts 13:2.
27) Can be Grieved: Is 63:10; Eph 4:30.
28) Can be Insulted: Heb 10:29.
29) Can be Lied to: Acts 5:3-4.
30) Can be Blasphemed: Mt 12:31-32.
31) Strives: Gen 6:3.
32) Is Knowledgeable: Is 40:13; Acts 10:19; 1 Cor 2:10-13.
33) Can be Vexed: Is 63:10.
34) Judges: Jn 16:8.
35) Prophesies: Acts 21:11; 28:25; 1 Tim 4:1.
36) Has Fellowship: 2 Cor 13:14.
37) Gives Grace: Heb 10:29.
38) Agrees: 1 Jn 5:7-8.
39) Offers Life: 2 Cor 3:6; Rev 22:17.
40) Is the Creator: Job 33:4.
4. Deity of the Holy Spirit: Direct Biblical Evidence
Genesis 1:2 …the Spirit of God was moving over the face of the waters. (cf. 41:38; Ex 31:3; 35:31; Num 24:2; 1 Sam 10:10; 11:6; 19:20, 23; 2 Chr 15:1; 24:20; Job 27:3; 33:4; Ezek 11:24)
Genesis 6:3 Then the LORD said, “My spirit shall not abide in man for ever,…” (cf. Is 30:1; 42:1; 44:3; 59:21; Ezek 36:27; 37:14; 39:29; Joel 2:28; Zech 4:6)
Nehemiah 9:20 Thou gavest thy good Spirit to instruct them,…
Job 33:4 The spirit of God has made me, and the breath of the Almighty gives me life.
Isaiah 34:16 …For the mouth of the LORD has commanded, and his Spirit has gathered them. (cf. Num 11:29; Is 48:16; Zech 7:12)
Isaiah 40:13 Who has directed the Spirit of the LORD, or as his counselor has instructed him? (cf. 63:14; Jud 3:10; 6:34; 11:29; 13:25; 14:6, 19; 15:4; 1 Sam 10:6; 16:13-14; 2 Sam 23:2; 1 Ki 18:12; 22:24; 2 Ki 2:16; 2 Chr 18:23; 20:14; Is 11:2; 40:13; 61:1; 63:14; Ezek 11:5; 37:1; Mic 2:7; 3:8)
Isaiah 63:10 …his holy Spirit…. (cf. 63:11)
Haggai 2:4-5 …I am with you, says the LORD of hosts,  according to the promise that I made you when you came out of Egypt. My Spirit abides among you; fear not.
Matthew 12:18 …I will put my Spirit upon him,… (Acts 2:17-18)
Luke 4:18 The Spirit of the Lord is upon me,… (Acts 5:9; 8:39)
John 4:24 God is spirit,…
Acts 5:3-4, 9 But Peter said, “Ananias, why has Satan filled your heart to lie to the Holy Spirit and to keep back part of the proceeds of the land?  While it remained unsold, did it not remain your own? And after it was sold, was it not at your disposal? How is it that you have contrived this deed in your heart? You have not lied to men but to God.”…  But Peter said to her, “How is it that you have agreed together to tempt the Spirit of the Lord?…”
Acts 28:25 So, as they disagreed among themselves, they departed, after Paul had made one statement: “The Holy Spirit was right in saying to your fathers through Isaiah the prophet:” [Is 6:8-10 is then quoted in 28:26-27; it applies the words cited to God; thus the Holy Spirit and God are equated; cf. Lk 1:70]
Romans 8:11 …the Spirit of him who raised Jesus from the dead dwells in you,… his Spirit which dwells in you. (cf. 2 Cor 1:22; Eph 3:16)
Romans 8:14 …the Spirit of God…. (cf. 8:9; Mt 3:16; 12:28)
1 Corinthians 2:10-11 God has revealed to us through the Spirit. For the Spirit searches everything, even the depths of God.  For what person knows a man’s thoughts except the spirit of the man which is in him? So also no one comprehends the thoughts of God except the Spirit of God.
1 Corinthians 2:14 The unspiritual man does not receive the gifts of the Spirit of God…. (cf. 2:12; 7:40; 12:3; Eph 4:30; 1 Jn 4:2)
1 Corinthians 3:16 Do you not know that you are God’s temple and that God’s Spirit dwells in you? (cf. 6:19)
2 Corinthians 3:17 Now the Lord is the Spirit, and where the Spirit of the Lord is, there is freedom. (cf. 3:18)
1 Thessalonians 4:8 …God, who gives his Holy Spirit to you.
5. 12 Descriptions Applied to All Three Divine Persons
Who raised Jesus from the dead?
Father: Gal 1:1; 1 Thess 1:10 Jesus: Jn 2:19; 10:17-18 Holy Spirit: Rom 8:11.
Who searches minds and hearts?
Father: Jer 17:10 Jesus: Rev 2:23 Holy Spirit: 1 Cor 2:10.
Who sanctifies believers?
Father: 1 Thess 5:23 Jesus: Heb 13:12 Holy Spirit: 1 Pet 1:2.
Who gives Christians words to speak?
Father: Mt 10:19-20 Jesus: Lk 21:14-15 Holy Spirit: Mk 13:11; Lk 12:11-12; Jn 14:26.
Who gave the new covenant?
Father: Jer 31:33-34 Jesus: Heb 8:1-13; 10:29; 12:24; 13:20 Holy Spirit: Heb 10:15-17.
Who is the creator?
Father: Gen 1:1; Is 44:24; Acts 17:24; Eph 3:9 Jesus: Jn 1:3; Col 1:16; Heb 1:8, 10 Holy Spirit: Job 33:4.
Who is our helper?
Father: Heb 13:6 Jesus: Heb 4:16 Holy Spirit: Rom 8:26.
Who are we baptized in the name of?
Father: Mt 28:19 Jesus: Mt 28:19 Holy Spirit: Mt 28:19.
Who comforts us?
Father: 2 Cor 1:3-4 Jesus: 2 Cor 1:5; cf. Jn 16:7 Holy Spirit: Acts 9:31.
Who gives us peace?
Father: 1 Cor 14:33; Phil 4:7 Jesus: Jn 14:27; Eph 2:14 Holy Spirit: Gal 5:22.
Who sends out Christians?
Father: Mt 9:38 Jesus: Mt 10:16; Mk 3:14; Jn 20:21 Holy Spirit: Acts 13:4.
Who calls Christians to ministry?
Father: Rom 8:28-30; Gal 1:15 Jesus: Rom 1:6 Holy Spirit: Acts 13:2.
6. Circumincession / Perichoresis: the Indwelling of the Three Persons in One Another
We need a definition of a definition for circumincession (Latin) or perichoresis (Greek) (probably known by one in five thousand persons, if that) for our present purposes in this section:
The penetration and indwelling of the three persons reciprocally in one another. In the Greek conception of the Trinity there is an emphasis on the mutual penetration of the three persons, thus bringing out the unity of the divine essence. In the Latin idea… the stress is more on the internal processions of the three divine persons. In both traditions, however, the fundamental basis of the Trinitarian perichoresis is the one essence of the three persons in God. (John A. Hardon. S. J., Modern Catholic Dictionary, Garden City, New York: Doubleday & Co., Inc., 1980, 415-416)
Perichoresis is also specifically applied to the two natures of Christ. This doctrine is especially evident in the following passages:
John 10:38 …the Father is in me and I am in the Father.
John 14:10-11 Do you not believe that I am in the Father and the Father in me? The words that I say to you I do not speak on my own authority; but the Father who dwells in me does his works.  Believe me that I am in the Father and the Father in me.…
John 17:21 …even as thou, Father, art in me, and I in thee.…
One way of demonstrating the explicit biblical basis for this doctrine is an examination of the indwelling of Christian believers. Who is it that is “in” us, after regeneration? The Bible teaches that all three of the Divine Persons are in us, because they are also “in” each other, as well as us, and cannot be separated from each other in function or purpose. No other conclusion can be drawn after seeing all the following passages, specifically categorized as they are:
God the Father indwells Christian believers:
1 Corinthians 3:16 Do you not know that you are God’s temple…? (cf. 3:17; Phil 2:13)
2 Corinthians 6:16 For we are the temple of the living God; as God said, “I will live in them and move among them, and I will be their God, and they shall be my people.” (cf. 9:14)
1 John 3:24 All who keep his commandments abide in him, and he in them.… (cf. Rom 15:33; Jas 4:8)
1 John 4:4 Little children, you are of God, and have overcome them; for he who is in you is greater than he who is in the world.
1 John 4:12 …if we love one another, God abides in us.…
1 John 4:15-16 Whoever confesses that Jesus is the Son of God, God abides in him, and he in God.  So we know and believe the love God has for us. God is love, and he who abides in love abides in God, and God abides in him.
2 John 1:9 Any one who goes ahead and does not abide in the doctrine of Christ does not have God;…
God the Son, Jesus indwells Christian believers:
John 6:56 He who eats my flesh and drinks my blood abides in me, and I in him.
John 14:18 I will not leave you desolate; I will come to you.
John 14:20 In that day you will know that I am in my Father, and you in me, and I in you. (cf. 14:21)
John 15:4 Abide in me, and I in you.… (cf. 15:5; 17:26)
Romans 8:10 …Christ is in you…. (cf. 2 Cor 13:5)
1 Corinthians 6:17 But he who is united to the Lord becomes one spirit with him.
Ephesians 3:17 …that Christ may dwell in your hearts through faith.…
Colossians 1:27 …Christ in you, the hope of glory. (cf. 3:15-16)
God the Holy Spirit indwells Christian believers:
Ezekiel 37:14 And I will put my Spirit within you, and you shall live,… (cf. Neh 9:20; Is 59:21; Jer 31:33-34; 32:40; Heb 8:10; 10:16)
John 14:16-17 And I will pray the Father, and he will give you another Counselor, to be with you for ever,  even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him; you know him, for he dwells with you, and will be in you.
Romans 8:9, 11 But you are not in the flesh, you are in the Spirit, if in fact the Spirit of God dwells in you. Any one who does not have the Spirit of Christ does not belong to him.…  If the Spirit of him who raised Jesus from the dead dwells in you, he who raised Christ Jesus from the dead will give life to your mortal bodies also through his Spirit which dwells in you. (cf. 8:14)
1 Corinthians 2:12 Now we have received not the spirit of the world, but the Spirit which is from God, that we might understand the gifts bestowed on us by God. (cf. 2:13: “possess the Spirit”)
1 Corinthians 3:16 Do you not know… that God’s Spirit dwells in you? (cf. 2 Cor 13:14)
God the Father and God the Son, Jesus indwell Christian believers:
John 14:23 …If a man loves me, he will keep my word, and my Father will love him, and we will come to him and make our home with him.
John 17:23 I in them and thou in me.…
Philippians 4:7 And the peace of God, which passes all understanding, will keep your hearts and your minds in Christ Jesus. (cf. 2 Cor 4:6; 2 Thess 3:5)
2 John 1:9 …he who abides in the doctrine has both the Father and the Son.
God the Father and God the Holy Spirit indwell Christian believers:
Romans 5:5 …God’s love has been poured into our hearts through the Holy Spirit which has been given to us.
1 Corinthians 6:19-20 Do you not know that your body is a temple of the Holy Spirit within you, which you have from God? You are not your own;  you were bought with a price. So glorify God in your body.
2 Corinthians 1:22 he has put his seal upon us and given us his Spirit in our hearts as a guarantee.
Ephesians 2:21-22 in whom the whole structure is joined together and grows into a holy temple in the Lord;  in whom you also are built into it for a dwelling place of God in the Spirit.
Ephesians 3:16 that according to the riches of his glory he may grant you to be strengthened with might through his Spirit in the inner man,
1 John 3:24 …And by this we know that he abides in us, by the Spirit which he has given us.
1 John 4:13 By this we know that we abide in him and he in us, because he has given us of his own Spirit.
God the Son, Jesus and God the Holy Spirit indwell Christian believers:
2 Corinthians 3:3 and you show that you are a letter from Christ delivered by us, written not with ink but with the Spirit of the living God, not on tablets of stone but on tablets of human hearts.
Galatians 4:6 …God has sent the Spirit of his Son into our hearts,…
Blessed John Henry Cardinal Newman’s words serve as a great summary of the above cross-referenced evidences:
It is the clear declaration of Scripture, which we must receive without questioning, that the Son and Spirit are in the one God, and He in Them… in naming the Father, we imply the Son and Spirit, whether They be named or not. Without this key, the language of Scripture is perplexed in the extreme.… (Arians of the Fourth Century, 1833 / 1871; London: Longmans, Green, and Co., 3rd edition, 1908; ch. 2, sec. 3)
[see also the companion paper: Jesus is God: Hundreds of Biblical Proofs (RSV Edition) ]
(initial research from 1982 [using KJV]; revised and reformatted for RSV edition in 2012)
Photo credit: The Holy Trinity, by Artus Wolffort (1581-1641) [public domain / Wikimedia Commons]