Carefully consider the following evidence from Scripture and for each passage ask yourself if God is three persons or one person.
The LORD our God, the LORD is one (Deuteronomy 6:4).
And one of the scribes came up and heard them disputing with one another, and seeing that he answered them well, asked him, "Which commandment is the first of all?" Jesus answered, "The first is, "Hear, O Israel: The Lord our God, the Lord is one; and you shall love the Lord your God with all your heart, and with all your soul, and with all your mind, and with all your strength.' The second is this, "You shall love your neighbor as yourself.' There is no other commandment greater than these." And the scribe said to him, "You are right, Teacher; you have truly said that he is one, and there is no other but he; and to love him with all the heart, and with all the understanding, and with all the strength, and to love one's neighbor as oneself, is much more than all whole burnt offerings and sacrifices." And when Jesus saw that he answered wisely, he said to him, "You are not far from the kingdom of God." (Mark 12:28-34).
The LORD your God who goes before you will Himself fight on your behalf, just as He did for you in Egypt before your eyes, and in the wilderness where you saw how the LORD your God has borne you, just as a man bears his son, in all the way which you have gone until you came to this place.' (Deuteronomy 1:31).
And you shall say to Pharaoh, "Thus says the LORD, Israel is My first-born son, and I say to you, "Let my son go that he may serve me"; if you refuse to let him go, behold, I will slay your first-born son.' (Exodus 4:22).
To you it was shown, that you might know that the LORD is God and there is no other besides Him. (Deuteronomy 4:35).
Do you thus repay the LORD, O foolish and unwise people? Is not He your Father who has bought you?... See now that I, I am He, And there is no God besides ME. (Deuteronomy 32:6-39).
He will cry to Me, 'You are My Father, My God, and the Rock of my salvation.' (Psalm 89:26).
O LORD, You are our Father, we are the clay, and You our potter and all of us are the work of Your hand. (Isaiah 64:8)
Have we not all One Father? Has not One God created us? (Malachi 2:10).
You are the Christ, the Son of the Living God. (Matthew 16:17).
My God, My God, why have you forsaken me. (Matthew 27:46).
I know that you do not have the love of God in you. I have come in the name of My Father, and you do not receive me. If another comes in his own name, him you will receive. How can you believe, who receive glory from one another, and do not seek the glory that comes from the Only God? Do not think that I shall accuse you to the Father.(John 5:43-44).
Believe in God; also believe in me (John 14:1).
The Father is greater than I (John 14:28; see 13:16).
Truly, truly, I say to you, a slave is not greater than his master, nor is one who is sent greater than the One who sent him. (John 13:16).
Father... this is eternal life, that they may know You, the only true God, and Jesus Christ whom You sent. (John 17:3).
I am ascending to My Father and your Father, to My God and your God. (John 20:17).
Men of Israel, listen to these words: Jesus the Nazarene, a man attested to you by God with miracles and wonders and signs which God performed through Him in your midst, just as you yourselves know.... "This Jesus God raised up again, to which we are all witnesses. And being therefore exalted at the right hand of God, and having received from the Father the promise of the Holy Spirit.... Let all the house of Israel therefore know assuredly that God has made this Jesus whom you crucified both Lord and Christ. (Acts 2:22-36).
The God of Abraham, and of Isaac, and of Jacob, the God of our fathers, has glorified His Son Jesus. (Acts 3:13).
...the God and Father of our Lord Jesus Christ. (Romans 15:5-6).
There is no God but one... for us there is one God, the Father out of whom are all things and we to Him and one Lord Jesus Christ through who are all things and we to him. (1 Corinthians 8:6).
The Head of Christ is God. (1 Corinthians 11:3).
Blessed be the God and Father of our Lord Jesus Christ, the Father of mercies and God of all comfort. (2 Corinthians 1:3).
The God and Father of our Lord Jesus. (2 Corinthians 11:31).
For he was crucified in weakness, but lives by the power of God (2 Corinthians 13:4).
But when the fullness of the time had come, God sent forth His Son, born of a woman, born under the law, to redeem tho se who were under the law, that we might receive the sonship. And because you are sons, God has sent forth the Spirit of His Son into your hearts, crying out, "Abba Father! (Galatians 4:4-6).
Blessed be the God and Father of our Lord Jesus Christ. (Ephesians 1:3).
The God of our Lord Jesus Christ, the Father of glory" (Ephesians 1:17).
I, then, a prisoner for the Lord, urge you to live in a manner worthy of the call you have received, with all humility and gentleness, with patience, bearing with one another through love, striving to preserve the unity of the spirit through the bond of peace, one body and one Spirit, as you were also called to the one hope of your call, one Lord, one faith, one baptism, one God and Father of all, who is over all and through all and in all. (Ephesians 4:1-6).
We give thanks to the God and Father of our Lord Jesus Christ" (Colossians 1:3).
For they themselves report concerning us what a welcome we had among you, and how you turned to God from idols, to serve a Living and True God, and to wait for His Son from heaven, whom He raised from the dead, Jesus who delivers us from the wrath to come.
(1 Thessalonians 1:9-10).
There is one God, and one mediator between God and men, the man Christ Jesus. (1 Timothy 2:5).
You have loved righteousness and hated lawlessness; Therefore God, your God, has anointed you with the oil of gladness more than your companions" (Hebrews 1:9).
In the days of his flesh, Jesus offered up prayers and supplications, with loud cries and tears, to Him Who was able to save him from death, and he was heard for his godly fear. Although he was a Son, he learned obedience through what he suffered; and being made perfect he became the source of eternal salvation to all who obey him, being designated by God a High Priest after the order of Melchizedek. (Hebrews 5:7-10).
Blessed be the God and Father of our Lord Jesus Christ" (1 Peter 1:3).
Now to Him who is able to keep you from stumbling, and to make you stand in the presence of His glory blameless with great joy, to the only God our Savior, through Jesus Christ our Lord, be glory, majesty, dominion and authority, before all time and now and forever. Amen. (Jude 1:25).
We know that the Son of God has come and has given us understanding, to know Him Who is True and we are in Him Who is True, in His Son Jesus Christ. This is the True God and eternal life. (1 John 5:20).
[Jesus] has made us kings and priests to his God and Father." (Revelation 1:6).
He who conquers, I will make him a pillar in the temple of my God. Never shall he go out of it, and I will write on him the name of my God, and the name of the city of my God, the new Jerusalem which comes down from my God out of heaven, and my own new name. (Rev 3:12).