Quran Said  Surely, disbelievers are those who said: ‘Allah is the third of the three (in a Trinity).’ But there is no Allah (god) (none who has the right to be worshipped) but One Ilaah (God -Allah). And if they cease not from what they say, verily, a painful torment will befall on the disbelievers among them” [al-Maa’idah 5:73].

Ibn Katheer (may Allah have mercy on him) said:

The correct view is that this was revealed concerning the Christians in particular, as was stated by Mujaahid and others.

Then the scholars differed concerning that. It was said that what is meant by that is their disbelief (kufr) because they say that there are three hypostases (“persons” of the trinity), namely the hypostasis of the Father, the hypostasis of the Son and the hypostasis of the Word that was transmitted from the Father to the Son – exalted be Allah far above what they say.

As-Suddi and others said: This was revealed concerning their making the Messiah and his mother into two gods with Allah, thus making Allah the third of three, according to this concept.(which is now concept  of Catholic.) As-Suddi said: This is like what Allah, may He be exalted, says at the end of the soorah (interpretation of the meaning):

“And (remember) when Allah will say (on the Day of Resurrection): "O 'Eesa (Jesus), son of Maryam (Mary)! Did you say unto men: 'Worship me and my mother as two gods besides Allah?'" He will say: "Glory be to You! It was not for me to say what I had no right (to say)” [al-Maa’idah 5:116]

Same concept is got by bible

Hosea ch11:9 jehovah(Allah) said for

only i am lord, i'm not man. none else beside me (isaiah 47:10) for these reason, Now a mediator is not of one but God is one [Galatians3:20, Douay Rheims version]. Jesus said never call any one Father[GOD] in earth. Reason  of your Father is one and heavenly. Do not want to call you teacher anyone. Evenly your teacher is one who is christ. (Matthew 23:9-10). Why do you call me lord lord but did not what i say? (luke 6:46). Not everyone who says to me lord, lord will enter into the kingdom of heaven.but he who does the will of my father who is in heaven [Matthew7:21 WEV]. 

Trinity  has also  other concept in Bible.Which shows now as Contradiction.

Jesus Said Father, Son and Holy ghost (spirit)are One(Kjv 1john5:7) But the hour cometh, and now is, when the true worshippers shall worship the Father in spirit and in truth: for the Father seeketh such to worship him. (John 4:23 KJV) God is a Spirit: and they that worship him must worship him in spirit and in truth. (John 4:24 KJV) Angel means  Holy spirit by according to online king James version dictionary and look below of it's screenshot and also enter this link (http://www.kingjamesbibledictionary.com/Dictionary/angel)

Angel (Holy spirit) forbid to do it. Such as-And I John saw these things, and heard them. And when I had heard and seen, I fell down to worship before the feet of the angel which shewed me these things (Revelation 22:8 KJV) Then saith he unto me, See thou do it not: for I am thy fellow servant, and of thy brethren the prophets, and of them which keep the sayings of this book: worship God. (Revelation 22:9 KJV)

Trinity is stupid concept according  to  biblical web proof-

The Trinity is a controversial doctrine; many Christians admit they don't understand it, while many more Christians don't understand it but think they do. .... The doctrine of the Trinity is one of the most difficult ideas in Christianity, but it's fundamental to Christians ... This idea that three persons add up to one individual seems like nonsense. And logically, it is. 

(www.bbc.co.uk/religion/religions/christianity/beliefs/trinity_1.shtml)