This is how the trinity is explained. God is three-in-one: God the Father, God the Son, and God the Holy Spirit. The three parts are separate, but coequeal personalities, and yet together, they form one being: God. Also explained with math, 1+1+1=3 1x1x1=1.
Those that believe in the trinity say that it is hard to understand, that it is not for man to understand the things of God. The bible has a different view though.
For nothing is secret that will not be revealed, nor anything hidden that will not be known and come to light. Luke 8:17 New King James Version also Luke 12:2
Here is a scripture that is used to explain the trinity.
In the beginning was the Word, and the Word was with God, and the Word was God.
John 1:1 New King James Version
This verse does not show the trinity but disproves it because there are only two persons and not three. This also does not mean that the Word is one being with God the Father. The Word was begotten from God the Father and therefore is brought forth from God. The Word is submissive to God the Father, so they can not be one in the same being or coequal, as shown below.
But I want you to know that the head of every man is Christ, the head of woman is man, and the head of Christ is God. 1 Corinthians 11:3 New King James Version
How is possible for Jesus to be almighty God, when the head of Christ is God?
You have heard Me say to you, ‘I am going away and coming back to you.’ If you loved Me, you would rejoice because I said, I am going to the Father, for My Father is greater than I.
John 14:28 New King James Version also John 10:29 Luke 22:42
Saying, “Father, if it is Your will, take this cup away from Me; nevertheless not My will, but Yours, be done.” Luke 22:42 New King James Version
The Son, the Word, Christ Jesus has always been subservient to God the Father.
For there are three that bear witness in heaven: the Father, the Word, and the Holy Spirit; and these three are one. 1 John 5:7 New King James Version
This verse does not appear in a single Greek manuscript before the 16th century, it was not written by John or inspired by God.
Before the mountains were brought forth, or ever You had formed the earth and the world, even from everlasting to everlasting, You are God. Psalm 90:2 New King James Version also Psalm 93:2
So this verse shows that the heavenly Father has no beginning and no end. But what about the Son?
In this the love of God was manifested toward us, that God has sent His only begotten Son into the world, that we might live through Him. 1 John 4:9 New King James Version
What of these words: only begotten?
This comes from the Greek word [μονογενής] translated in English: monogenēs, meaning single of its kind, only, used of only sons, used of Christ, denotes the only begotten son of God.
(Lexicon :: Strong's G3439)
Monogenēs comes from the Greek root words [μόνος] monos: meaning alone, only, by themselves. (Lexicon :: Strong's G3441)
And [γίνομαι] ginomai: meaning to become, i.e. to come into existence.
(Lexicon :: Strong's G1096)
Then we have this verse: He is the image of the invisible God, the firstborn over all creation. Colossians 1:15 New King James Version
Firstborn comes from the Greek word [πρωτότοκος] prōtotokos: meaning the firstborn,
of man or beast, of Christ, the first born of all creation.
The Son was the only begotten of his Father, therefore the Son Jesus Christ had a beginning. If the Father has no beginning, but the Son does then they can not be one in the same. Jesus was the son long before coming to earth.(John 17:5, 24)
“But of that day and hour no one knows, not even the angels of heaven, but My Father only. Matthew 24:36 New King James Version
The day and hour is known only to one, God the Father, so how can the Father and Son be one being if the Son does not know the day or hour of his own return?
What about the Holy Spirit?
Trinitarians say the Holy spirit is a 3rd person of the same God. But what do the scriptures say?
“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. John 15:26 New King James Version
So the holy spirit is not a 3rd person but the spirit of the father himself, as it proceeds from the father.
But when they deliver you up, do not worry about how or what you should speak. For it will be given to you in that hour what you should speak; 20 for it is not you who speak, but the Spirit of your Father who speaks in you. Matthew 10:20 NKJV
Again we see that the spirit that is in us, is the spirit of the father, not a 3rd person.
During the time of the Apostles.
False doctrine was already seeping into the true church.
I marvel that you are turning away so soon from Him who called you in the grace of Christ, to a different gospel, 7 which is not another; but there are some who trouble you and want to pervert the gospel of Christ. 8 But even if we, or an angel from heaven, preach any other gospel to you than what we have preached to you, let him be accursed.
Galatians 1:6-8 New King James Version
But shun profane and idle babblings, for they will increase to more ungodliness. 17 And their message will spread like cancer. Hymenaeus and Philetus are of this sort, 18 who have strayed concerning the truth, saying that the resurrection is already past; and they overthrow the faith of some.
2 Timothy 2:16-18 New King James Version
For certain men have crept in unnoticed, who long ago were marked out for this condemnation, ungodly men, who turn the grace of our God into lewdness and deny the only Lord God and our Lord Jesus Christ.
Jude 4 New King James Version
Little children, it is the last hour; and as you have heard that the Antichrist is coming, even now many antichrists have come, by which we know that it is the last hour. 19 They went out from us, but they were not of us; for if they had been of us, they would have continued with us; but they went out that they might be made manifest, that none of them were of us.
1 John 2:18-19 New King James Version
I have not written to you because you do not know the truth, but because you know it, and that no lie is of the truth.
22 Who is a liar but he who denies that Jesus is the Christ? He is antichrist who denies the Father and the Son. 23 Whoever denies the Son does not have the Father either; he who acknowledges the Son has the Father also. 1 John 2:21-23 New King James Version
But The statement may arise, I do not deny Jesus or the Father. But, if you believe in the trinity or a form of it, then as apostle Paul wrote ...you are turning away ... to a different gospel...to those that pervert the gospel of Christ. Galatians 1:6-8 New King James Version
If those that believe in the trinity or a form of it, they do believe in a different version of the gospel than what Jesus and the apostles have taught, then they do not believe in the true Christ or the true Father and are denying them.
The coming of the lawless one is according to the working of Satan, with all power, signs, and lying wonders, 10 and with all unrighteous deception among those who perish, because they did not receive the love of the truth, that they might be saved. 11 And for this reason God will send them strong delusion, that they should believe the lie, 12 that they all may be condemned who did not believe the truth but had pleasure in unrighteousness.
2 Thessalonians 2:9-15
Those that believe in the the lie, is there no hope?
Jeremiah 29:13 New King James Version
But without faith it is impossible to please Him, for he who comes to God must believe that He is, and that He is a rewarder of those who diligently seek Him.
Hebrews 11:6 New King James Version
“Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you.
Matthew 7:7 New King James Version
So then which one, Believe in the lie or seek the truth?