Trinity

1 John 5:7 (king james version)

For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one. 

Three in one has been removed by Christian scholars from Revised Standard Version

1 John 5: 6-8 (Revised Standard Version)

6-This is the One who came by water and blood, Jesus Christ—not by water alone, but by water and blood. And it is the Spirit who testifies to this, because the Spirit is the truth. 
7-For there are three that testify:
8-the Spirit, the water, and the blood — and these three are in agreement. 

The argument based on John 10:30-37

John 10:30-  I and the Father are one.

So what is the contex for this statement??..there is no other way but its connected with the next verses…

John 10:31-33
31-At this, the Jews again picked up stones to stone Him.
32-But Jesus answered, “I have shown you many good works from the Father. For which of these do you stone Me?” 
33-“We are not stoning You for any goodwork, said the Jews, “but for blasphemy, because You,who are a man, declare Yourself to be God.” 

It seems Jews claimed that Jesus consider himself as God but Jesus didn’t accept it or denied it becaused its related with the contex meaning of ‘god’ according to those jews (linguistic boundation) ..not literally god is the contex of divinity but it is in the contex of godly work for real God who gave those authority.

John 10:34
Jesus replied, “Is it not written in your Law: ‘I have said you are gods’?

 To defend himself Jesus replied by quote the law of moses (Torah- old testament) which is psalm 82:6

Psalm 82:6 

said, "You are gods, And all of you are sons of the Most High. “

John 10:35-36

 35-If he called them GODS TO WHOM THE WORD OF GOD CAME — and the Scripture cannot be broken — 

36-THEN WHAT ABOUT THE ONE WHOM THE FATHER SANCTIFIED AND SENT INTO THE WORLD? How then can you accuse Me of blasphemy’ for stating that I am the Son of God?

From the verses John 10: 35-36 the ‘god’ in the contex for Jesus situation and the past jews(psalm 82:6) is the one whom bring the word of God or the one whom sent by Father into the world to do the godly work..Jesus truly the son of god metaphorically becaused he did bring the word of God and sent by God to fullfill the godly mission (mission from God). The same situation like Moses the one who received the godly authority upon falsehood and evil (Pharaoh).

Exodus 7:1

Then the LORD said to Moses, "See, I make you as God to Pharaoh, and your brother Aaron shall be your prophet.

Jesus clearly state if he did not doing his Father work so don’t believe in him but the fact is he did his task as someone who sent by the Father

John 10:37
 If I am not doing the works of My Father,then do not believe Me.

Bart Ehrman on the Origins of the Trinity

LOGICAL EXPLAINATION (basic calculation):

whole = fully, part= not fully/half

1 + 1 + 1 = 3
1 part + 1 part + 1 part = 3 part = 1 whole
1 whole + 1 whole + 1 whole = 3 whole ( not 1 whole nor 1 part)

Water (part 1) + Blood (part 2) + water (part 3) = 3 part = 1 whole mixture that combine (not 1 part)
(combination/mixture= inseperable but different kind of "part" still seperable in element or essence to form 1 different mixture-not original element )

Father(part 1) + Jesus (part 2) + Holy Spirit (part 3) = 3 part = 1 whole (not 1 part)
...if we believe this kind of calculation so Jesus is not fully God becaused he was "part" to make as a whole (combination/mixture= inseparable but still different kind of "part" in element or essence)

Father ( whole 1) + Jesus (whole 2) + Holy spirit (whole 3)= 3 whole (not 1 whole)
..if Jesus was fully god so he's being another "whole"/"fully" which means seperable (not part of). 

John 10:30 " I and my Father are one " 

What did Jesus mean saying 'I and my Father are One'!

Inequality Between Three

Father is Greater than Jesus

Ye have heard how I said unto you, ‘I go away and come again unto you.’ If ye loved Me, ye would rejoice because I said, ‘I go unto the Father,’ for My Father is greater than I.(JOHN 14:28)

Father is Greater than ALL

My Father who has given them to Me is greater than all. No one can snatch them out of My Father’s hand.(John 10:29 )

So Jesus and the Father (God) are not EQUAL

And Paul declares that the head of every woman is her husband, the head of every man is Christ, and the head of Christ is God (see 1 Corinthians 11:3).

Anyone who speaks a word against the Son of Man will be forgiven, but anyone who speaks against the Holy Spirit will not be forgiven, either in this age or in the age to come. – Matthew 12:32

“But about that day or hour no one knows, not even the angels in heaven, nor the Son, but only the Father” – Matthew 24:36

Conclusion

People of the Book, do not go to excess in your religion, and do not say anything about God except the truth: the Messiah, Jesus, son of Mary, was nothing more than a messenger of God, His word, directed to Mary, a spirit from Him. So believe in God and His messengers and do not speak of a 'Trinity'—stop, that is better for you—God is only one God, He is far above having a son, everything in the heavens and earth belongs to Him and He is the best one to trust.

— Qur'an, sura 4 (An-Nisa), ayat 171

O People of the Scripture, do not commit excess in your religion or say about Allah except the truth. The Messiah, Jesus, the son of Mary, was but a messenger of Allah and His word which He directed to Mary and a soul [created at a command] from Him. So believe in Allah and His messengers. And do not say, "Three"; desist - it is better for you. Indeed, Allah is but one God. Exalted is He above having a son. To Him belongs whatever is in the heavens and whatever is on the earth. And sufficient is Allah as Disposer of affairs.
(Quran-4:171)

Those who say, "God is the Messiah, son of Mary," have defied God. The Messiah himself said; "Children of Israel, worship God, my Lord and your Lord." If anyone associates others with God, God will forbid him from the Garden, and Hell will be his home. No one will help such evildoers. Those people who say that God is the third of three are defying [the truth]: there is only One God. If they persist in what they are saying, a painful punishment will afflict those of them who persist. Why do they not turn to God and ask his forgiveness, when God is most forgiving, most merciful? The Messiah, son of Mary, was only a messenger; other messengers had come and gone before him; his mother was a virtuous woman; both ate food. See how clear We make these signs for them; see how deluded they are.

— Qur'an, sura 5 (Al-Ma'ida), ayat 72-75[4]

John 20:17  King James Version (KJV)

Jesus saith unto her, Touch me not; for I am not yet ascended to my Father: but go to my brethren, and say unto them, I ascend unto my Father, and your Father; and to my God, and your God.

Oxford Professor Gives Historical Proof Muslims are Right on Trinity

Who Created the World? Jeff Durbin vs Nabeel Qureshi (Trinity Confusion!)