The mystery doctrine of the Trinity, (proof verses are offered below), resolves the seeming contradiction that both Father God and God the Son are one, including the Holy Spirit. John 17:21 "that they all may be one, as You, Father, are in Me, and I in You; that they also may be one in Us, that the world may believe that You sent Me." The doctrine has baffled many, because we're limited to finite human experience, and because unless we examine the whole counsel of God, in the Bible, we can overlook key verses that make plurality and oneness plain; a bit like our university(s) that pursue unity with diversity, and the body of Christ.
1 John 5:6,7;
For there are three that bear witness in heaven: the Father, the Word, and the Holy Spirit; and these three are one. John 10:30 "I and My Father are one."
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'?
Behold, He is coming with clouds, and every eye will see Him, even they who pierced Him. And all the tribes of the earth will mourn because of Him. Even so, Amen. "I am the Alpha and the Omega, the Beginning and the End," says the Lord, "who is and who was and who is to come, the Almighty."
Jews who hold that God the Father is alone also hold that a messiah is to come, who will usher in God's kingdom. But a messiah can't resolve entropy throughout the cosmos, creating a utopia, or give us an afterlife unless he is infinite/divine, like Jesus Christ claims to be - as demonstrated by repeatedly raising the dead on demand. The heptadic structure of the Bible shows it to be God inspired. The heptadic signature of the genealogy of Jesus Christ shows the Holy Spirit authenticates Jesus' divine infinite person.
Some have missed the Old (& New) Testament verses that indicate the God head is a plurality of 3 persons in one God, referenced below.
Genesis 1:26, 3:22, Isaiah 6:3,8
No one has seen God at any time. The only begotten Son, who is in the bosom of the Father, He has declared Him.
And the Father Himself, who sent Me, has testified of Me. You have neither heard His voice at any time, nor seen His form.
Not that anyone has seen the Father, except He who is from God; He has seen the Father.
God is Spirit, and those who worship Him must worship in spirit and truth.
Therefore know this day, and consider it in your heart, that the Lord Himself is God in heaven above and on the earth beneath; there is no other.
You shall have no other gods before Me.
that all the peoples of the earth may know that the Lord is God; there is no other.
Thus says the Lord, the King of Israel,
And his Redeemer, the Lord of hosts:
I am the First and I am the Last;
Besides Me there is no God.
I am the Lord, and there is no other;
There is no God besides Me.
Truly You are God, who hide Yourself,
O God of Israel, the Savior.
Then you shall know that I am in the midst of Israel:
I am the Lord your God
And there is no other.
My people shall never be put to shame.
So the scribe said to Him, "Well said, Teacher. You have spoken the truth, for there is one God, and there is no other but He."
Nor is there salvation in any other (ie Jesus Christ), for there is no other name under heaven given among men by which we must be saved.
Ultimate Bible Study Suite KJV
TRINITY (THE HOLY)
Genesis 1:26"Then God said, "Let Us make man in Our image, according to Our likeness";
3:22 Then the Lord God said, "Behold, the man has become like one of Us";
And one cried to another and said: "Holy, holy, holy is the Lord of hosts;
Also I heard the voice of the Lord, saying: "Whom shall I send, And who will go for Us?"
"Behold! My Servant whom I uphold, My Elect One in whom My soul delights! I have put My Spirit upon Him; He will bring forth justice to the Gentiles."
"Come near to Me, hear this: I have not spoken in secret from the beginning; From the time that it was, I was there. And now the Lord God and His Spirit Have sent Me."
"The Spirit of the Lord God is upon Me, Because the Lord has anointed Me To preach good tidings to the poor; He has sent Me to heal the brokenhearted, To proclaim liberty to the captives, And the opening of the prison to those who are bound; To proclaim the acceptable year of the Lord, And the day of vengeance of our God; To comfort all who mourn, To console those who mourn in Zion, To give them beauty for ashes, The oil of joy for mourning, The garment of praise for the spirit of heaviness; That they may be called trees of righteousness, The planting of the Lord, that He may be glorified."
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."
"Behold! My Servant whom I have chosen, My Beloved in whom My soul is well pleased! I will put My Spirit upon Him, And He will declare justice to the Gentiles."
But if I cast out demons by the Spirit of God, surely the kingdom of God has come upon you.
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,
I indeed baptized you with water, but He will baptize you with the Holy Spirit.
And the angel answered and said to her, "The Holy Spirit will come upon you, and the power of the Highest will overshadow you; therefore, also, that Holy One who is to be born will be called the Son of God."
John answered, saying to all, "I indeed baptize you with water; but One mightier than I is coming, whose sandal strap I am not worthy to loose. He will baptize you with the Holy Spirit and fire."
And the Holy Spirit descended in bodily form like a dove upon Him, and a voice came from heaven which said, "You are My beloved Son; in You I am well pleased."
"The Spirit of the Lord is upon Me, Because He has anointed Me To preach the gospel to the poor; He has sent Me to heal the brokenhearted, To proclaim liberty to the captives And recovery of sight to the blind, To set at liberty those who are oppressed; To proclaim the acceptable year of the Lord."
And John bore witness, saying, "I saw the Spirit descending from heaven like a dove, and He remained upon Him. I did not know Him, but He who sent me to baptize with water said to me, 'Upon whom you see the Spirit descending, and remaining on Him, this is He who baptizes with the Holy Spirit.' And I have seen and testified that this is the Son of God."
For He whom God has sent speaks the words of God, for God does not give the Spirit by measure.The Father loves the Son, and has given all things into His hand.
But the Helper, the Holy Spirit, whom the Father will send in My name, He will teach you all things, and bring to your remembrance all things that I said to you.
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.
Nevertheless I tell you the truth. It is to your advantage that I go away; for if I do not go away, the Helper will not come to you; but if I depart, I will send Him to you.
However, when He, the Spirit of truth, has come, He will guide you into all truth; for He will not speak on His own authority, but whatever He hears He will speak; and He will tell you things to come. He will glorify Me, for He will take of what is Mine and declare it to you. All things that the Father has are Mine. Therefore I said that He will take of Mine and declare it to you.
And being assembled together with them, He commanded them not to depart from Jerusalem, but to wait for the Promise of the Father, "which," He said, "you have heard from Me; for John truly baptized with water, but you shall be baptized with the Holy Spirit not many days from now."
Acts 2:33; Acts 10:36-38;
Therefore being exalted to the right hand of God, and having received from the Father the promise of the Holy Spirit, He poured out this which you now see and hear.
The word which God sent to the children of Israel, preaching peace through Jesus Christ -- He is Lord of all -- that word you know, which was proclaimed throughout all Judea, and began from Galilee after the baptism which John preached: how God anointed Jesus of Nazareth with the Holy Spirit and with power, who went about doing good and healing
concerning His Son Jesus Christ our Lord, who was born of the seed of David according to the flesh, and declared to be the Son of God with power according to the Spirit of holiness, by the resurrection from the dead.
But you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. Now if anyone does not have the Spirit of Christ, he is not His. And if Christ is in you, the body is dead because of sin, but the Spirit is life because of righteousness. But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ from the dead will also give life to your mortal bodies through His Spirit who dwells in you.
1 Corinthians 2:10,11;
1 Corinthians 6:19;
Or do you not know that your body is the temple of the Holy Spirit who is in you, whom you have from God, and you are not your own?
1 Corinthians 8:6;
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.
2 Corinthians 1:21,22;
Now He who establishes us with you in Christ and has anointed us is God, who also has sealed us and given us the Spirit in our hearts as a guarantee.
2 Corinthians 5:5;
Now He who has prepared us for this very thing is God, who also has given us the Spirit as a guarantee.
2 Corinthians 13:14;
The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Spirit be with you all.
And because you are sons, God has sent forth the Spirit of His Son into your hearts, crying out, "Abba, Father!"
2 Thessalonians 2:13,14,16;
1 Timothy 3:16;
And without controversy great is the mystery of godliness: God was manifested in the flesh, Justified in the Spirit, Seen by angels, Preached among the Gentiles, Believed on in the world, Received up in glory.
But when the kindness and the love of God our Savior toward man appeared, not by works of righteousness which we have done, but according to His mercy He saved us, through the washing of regeneration and renewing of the Holy Spirit, whom He poured out on us abundantly through Jesus Christ our Savior, that having been justified by His grace we should become heirs according to the hope of eternal life.
how much more shall the blood of Christ, who through the eternal Spirit offered Himself without spot to God, cleanse your conscience from dead works to serve the living God?
For Christ also suffered once for sins, the just for the unjust, that He might bring us to God, being put to death in the flesh but made alive by the Spirit
1 John 5:6,7;
For there are three that bear witness in heaven: the Father, the Word, and the Holy Spirit; and these three are one.
"I am the Alpha and the Omega, the Beginning and the End," says the Lord, "who is and who was and who is to come, the Almighty."
To him who overcomes I will grant to sit with Me on My throne, as I also overcame and sat down with My Father on His throne. He who has an ear, let him hear what the Spirit says to the churches.