From the Christian point of view, it's corrupted because it doesn't say Jesus is part of God.
The irony is that Jesus wasn't originally part of God in Christianity either.

Well, during the islamic revolution, Allah directed prayer energy towards The Kaaba. Like, plasmonics. When muslims pray in the direction of Kaaba, their wishes that they make show up in a sort of App to Allah. Then considering if the wishes are good for their future, Allah approves it or wont. Considering what is good for them :) When you pray namaz in the direction of The Kaaba, then it goes directly to Allah. And He gets to decide if He approves them or future-presents them, based on what is good for you :)

So which Quran are you talking about. There are about 26 of them that are widely distributed and they all disagree with each other. In fact the canon of the Quran was only established a few years ago.

One more thing. The dark passages of the Quran. Did you know that if you took those passages that don't make any sense as written, keeping the consonant letters and changed the Arabic vowel sounds with Aramaic vowel sounds the entire passages make sense and are ancient Christian hymns and poems dating from the 3rd and 4 centuries.

Who says the Quran is corrupted?

Why don't you just assume it is very sensible human philosophy?

I do assume that it’s the the third tome. I see tho Quran the same as the Torah or Bible. I personally think everything written by humans is corrupted in some way, especially those books - in their treatment of women.
Of course everyone who believes and follows these doctrines will say another is corrupted.

I read it (the Abdullah Yusuf Ali translation) and wasn't impressed. A lot of it seemed to be a reiteration of parts of the Bible, written by someone who had read it a long time before and didn't remember it that well. Also, the constant repetition of "righteous will go to heaven, unrighteous to hell" made me wonder if the author wasn't somewhat obsessed in that area. I fail to see why a billion people think this is the greatest book ever written, but to each his own.