I don’t know any Bible topic that is harder to explain than the fact that God is a Trinity. Him being a Trinity means that He is one God who exists in three distinct persons. Even though He is God the Father, God the Son (Jesus), and God the Holy Spirit, these three distinct persons are one. God is one God, not three. As it says in the Constitution & Bylaws of many a Baptist church: “The one God is revealed to us as Father, Son, and Holy Spirit, each with distinct personal attributes, but without division of nature, essence, or being.”

Well, I don’t have the audacity to think that I’m going to sit down and write a blog post that is going to clear up all the confusion regarding the doctrine of the Trinity. After all, the church has been working on that project for some 2,000 years now and hasn’t mastered it yet. So, what I’m going to do is simply offer a list of many of the relevant passages of scripture that speak to the issue and include just a touch of commentary after each passage. In this way, I’ll just let the Bible do its own teaching. I’ll cite the passages in the order in which they are found in scripture, and I’ll use the New King James Version for all of them. These passages will constitute the body of this post. Here goes:

1. Genesis 1:1: In the beginning God created the heavens and the earth. (The Hebrew word translated in this verse as “God” is Elohim. What’s significant about that is the fact that Elohim is a plural word. You see, from the very first verse of the Bible, God is laying the groundwork for the idea that He is a triune being.)
2. Genesis 2:26: Then God said, “Let Us make man in Our image, according to Our likeness… (Note the words “Us” and “Our.”)
3. Genesis 3:22: Then the Lord God said, “Behold, the man has become like one of Us, to know good and evil…. (Here again God uses the word “Us” concerning Himself.)
4. Genesis 11:7: “Come, let Us go down and there confuse their language, that they may not understand one another’s speech.” (God spoke these words about the building of the Tower of Babel.)
5. Deuteronomy 6:4: “Hear, O Israel: The Lord our God, the Lord is one!” (These words are the opening words for the Jewish prayer called the Shema, which is the most famous prayer in Judaism.)
6. Psalm 2:7,12: “I will declare the decree: The Lord has said to Me, Today I have begotten You….Kiss the Son, lest He be angry, And you perish in the way, When His wrath is kindled but a little. Blessed are those who put their trust in Him. (Note the capitalized titles in this Messianic passage. They indicate that God the Father has a Son who is fully divine Himself and in whom we should place our trust.)
7. Proverbs 30:4: Who has ascended into heaven, or descended? Who has gathered the wind in His fists? Who has bound the waters in a garment? Who has established all the ends of the earth? What is His name, and what is His Son’s name, If you know? (This is another Old Testament passage that teaches that God has a Son.)
8. Isaiah 6:8: Also I heard the voice of the Lord, saying: “Whom shall I send, And who will go for Us?” (Here again we see God using the word “Us” in reference to Himself, even though in this instance He also uses the word “I.”)
9. Isaiah 9:6: For unto us a Child is born, Unto us a Son is given; And the government will be upon His shoulder. And His name will be called Wonderful, Counselor, Mighty God, Everlasting Father, Prince of Peace. (New Testament passages such as Luke 2:11 and John 1:45 leave no doubt that the Messiah spoken of in this passage is none other than Jesus. That’s important to understand because this passage calls Jesus not only “Everlasting Father” but also “Mighty God.” Both of those titles can also rightly serve as titles for God the Father.)  
10. Matthew 3:16-17: When He had been baptized, Jesus came up immediately from the water; and behold, the heavens were opened to Him, and He saw the Spirit of God descending like a dove and alighting upon Him. And suddenly a voice came from heaven, saying, “This is My beloved Son, in whom I am well pleased.” (This passage finds the Trinity on full display. God the Son is baptized. God the Holy Spirit comes down from heaven to rest upon Him. God the Father speaks from heaven.)
11. Matthew 17:5: While he was still speaking, behold, a bright cloud overshadowed them; and suddenly a voice came out of the cloud, saying, “This is My beloved Son, in whom I am well pleased. Hear Him!” (As He had done at Jesus’ baptism, here God the Father speaks directly from heaven concerning Jesus and calls Him “My beloved Son.”)
12. Matthew 28:18-20: And Jesus came and spoke to them, saying, “All authority has been given to Me in heaven and on earth. Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age.” Amen. (Notice here that Jesus commands His followers to baptize in the singular “name” of the Father, the Son, and the Holy Spirit.)
13. John 1:1-3,14: In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things were made through Him, and without Him nothing was made that was made…And the Word became flesh and dwelt among us, and we beheld His glory, the glory as of the only begotten of the Father, full of grace and truth. (These verses teach that not only was Jesus with God in the beginning but that He was God. He was the Creator.)
14. John 5:22: “For the Father judges no one, but has committed all judgment to the Son.” (Jesus taught that the divine Judge of the Universe is none other than Himself, and that certainly speaks to His divinity.)
15. John 8:58: Jesus said to them, “Most assuredly, I say to you, before Abraham was, I AM.” (No Jew had to be told what Jesus meant in claiming the title “I AM.” Moses had asked God, “What shall I say to your people when they ask me, ‘Who sent you to us?'” God had responded by saying, “Thus you shall say to the children of Israel, ‘I AM’ has sent me to you” (Exodus 3:14). Jesus claimed to be that same God, and that’s why the Jews immediately took up stones and attempted to stone Him to death for blasphemy.)  
16. John 10:30: “I and My Father are one.” (By Jesus’ own teaching, He and God the Father are one even though they are each a distinct person. The Jewish religious leaders certainly took His statement that way. A few verses later they tried to stone Him for the blasphemy of making Himself God.)
17. John 12:41: These things Isaiah said when he saw His glory and spoke of Him. (This verse hearkens back to the vision that Isaiah has of God in Isaiah 6:1-13. John’s use of the capitalized words “His” and “Him” in reference to Jesus shows that Jesus was the God in Isaiah’s vision.)
18. John 14:9: Jesus said to him, “Have I been with you so long, and yet you have not known Me, Philip? He who has seen Me has seen the Father; so how can you say, “Show us the Father?” (Even though God the Son and God the Father are each distinct persons, their oneness means that, in essence, to see one is to see the other.) 
19. John 15:26: “But when the Helper comes, whom I shall send to you from the Father, the Spirit of truth who proceeds from the Father, He will testify of Me.” (The capitalized title “Helper” is a reference to God the Holy Spirit. Notice that the Holy Spirit proceeds from God the Father and testifies of God the Son.) 
20. John 17:5: “And now, O Father, glorify Me together with Yourself, with the glory which I had with You before the world was.” (Here Jesus speaks of having a divine glory in a time before Genesis 1:1, just like the glory of God the Father.) 
21. John 20:28: And Thomas answered and said to Him, “My Lord and my God!” (Thomas called Jesus “my God” and Jesus didn’t correct him.)
22. Acts 2:32-33: This Jesus God has raised up, of which we are all witnesses. Therefore being exalted to the right hand of God the Father, and having received from the Father the promise of the Holy Spirit, He poured out this which you now see and hear. (These verses teach that Jesus is right now seated at the right hand of God the Father. He’s not God the Father, but He is seated on His right side, which was always the side of favor in the Jewish placements.)
23. Acts 5:3-4: But Peter said, “Ananias, why has Satan filled your heart to lie to the Holy Spirit and keep back part of the price of the land for yourself? While it remained, was it not your own? And after it was sold, was it not in your own control? Why have you conceived this thing in your heart? You have not lied to men but to God.” (Notice the way that Peter interchangeably uses the Holy Spirit and God. First, he says that Ananias lied to the Holy Spirit. Second, he says that Ananias lied to God. The logical conclusion to be drawn is that the Holy Spirit is God.)
24. Acts 7:55-56: But he, being full of the Holy Spirit, gazed into heaven and saw the glory of God, and Jesus standing at the right hand of God, and said, “Look! I see the heavens opened and the Son of Man standing at the right hand of God!” (This is another passage that places Jesus in a seat of divine prominence at the right hand of God the Father. The classic interpretation of the passage is that Jesus had stood up to receive the soul of the soon-to-be martyred Stephen.)
25. Acts 13:2: As they ministered to the Lord and fasted, the Holy Spirit said, “Now separate to Me Barnabas and Saul for the work to which I have called them.” (This verse equates the Holy Spirit to “the Lord” and speaks of the Holy Spirit doing God’s job of calling people to the mission field.)
26. Acts 20:28: “Therefore take heed to yourselves and to all the flock, among which the Holy Spirit has made you overseers to shepherd the church of God which He purchased with His own blood.” (This is a significant passage because it speaks of Jesus and the Holy Spirit as each being God. According to Paul’s words, the Holy Spirit had made these men the overseers — the shepherds, the pastors — of the church of God. That implies that the Holy Spirit is God. Also, Paul says that God purchased the church with His own blood. That, of course, is a reference to Jesus dying on the cross, and it means that Jesus is God as well.)
27. Acts 28:25-26: So when they did not agree among themselves, they departed after Paul had said one word: “The Holy Spirit spoke rightly through Isaiah the prophet to our fathers, saying…” (At this point Paul quotes verses 9 and 10 of the familiar Isaiah 6:1-13 Messianic passage. Interestingly, whereas John 12:41 proves that Jesus was the God in Isaiah’s vision, this passage teaches that it was the Holy Spirit who actually spoke the Lord’s words in that vision. The clear indication is that Jesus and the Holy Spirit, though distinct from each other, are in essence one.)
28. Romans 9:5: …of whom are the fathers and from whom, according to the flesh, Christ came, who is over all, the eternally blessed God. Amen. (Not only is Jesus the Lord over everything, Paul also called him “the eternally blessed God.”)
29. 1 Corinthians 8:4-6: Therefore concerning the eating of things offered to idols, we know that an idol is nothing in the world, and that there is no other God but one. For even if there are so-called gods, whether in heaven or on earth (as there are many gods and many lords), yet for us there is one God, the Father, of whom are all things, and we for Him; and one Lord Jesus Christ, through whom are all things, and through whom we live. (Paul doesn’t mention God the Holy Spirit in these verses, but he does specifically name God the Father and the Lord Jesus Christ, and yet still affirms, “…there is no other God but one.”)
30. 2 Corinthians 3:17: Now the Lord is the Spirit; and where the Spirit of the Lord is, there is liberty. (Here we see that the Holy Spirit is the Lord. In other words, He is God.)
31. Galatians 4:6: And because you are sons, God has sent forth the Spirit of His Son into your hearts, crying out, “Abba, Father!” (All three members of the Trinity are mentioned in this verse. Jesus is God the Son. God the Holy Spirit is referred to as the Spirit of Jesus. And God the Holy Spirit’s indwelling of the Christian allows the Christian the right to refer to God the Father as “Father.”)
32. Colossians 2:9: For in Him dwells all the fullness of the Godhead bodily. (The term “the Godhead” refers to the Trinity.)
33. Titus 2:13: …looking for the blessed hope and glorious appearing of our great God and Savior Jesus Christ. (Here again Paul doesn’t hesitate to call Jesus “our great God.”) 
34. Hebrews 1:1-2: God, who at various times and in various ways spoke in time past to the fathers by the prophets, has in these last days spoken to us by His Son, whom He has appointed heir of all things, through whom also He made the worlds. (This is a parallel passage to John 1:1-3, both passages teaching that Jesus is the Creator mentioned in Genesis 1:1.)
35. Hebrews 1:8: But to the Son He says: “Your throne, O God, is forever and ever; A scepter of righteousness is the scepter of Your kingdom.” (The teaching is that Jesus, the Son, is God.) 
36. Hebrews 10:12: But this Man, after He had offered one sacrifice for sins forever, sat down at the right hand of God. (This verse is yet another one that places Jesus in a role of divinity at the right hand of God the Father.) 
37. James 2:19: You believe that there is one God. You do well. Even the demons believe — and tremble! (You see, we do well to believe that God is a singular God.)
38. 2 Peter 1:1: Simon Peter, a bondservant and apostle of Jesus Christ, To those who have obtained like precious faith with us by the righteousness of our God and Savior Jesus Christ. (Peter referred to Jesus as “our God.”)
39. 1 John 5:7: For there are three that bear witness in heaven: the Father, the Word, and the Holy Spirit, and these three are one. (The title “the Word” is a title for Jesus.)
40. Revelation 22:8-9: Now I, John, saw and heard these things. And when I heard and saw, I fell down to worship before the feet of the angel who showed me these things. Then he said to me, “See that you do not do that. For I am your fellow servant, and of your brethren the prophets, and of those who keep the words of this book. Worship God.” (This passage is significant because of the angel’s words, “Worship God.” Jesus receives such worship in Revelation 5:8-14.)