The accepted view amongst Muslims, and especially Shiite's is that no
alteration has occurred in the holy Qoran, and that the text that is in our
hands is the whole Qoran that was revealed to the great Prophet (peace be
upon him and his progeny) without being added nor loss.
There are a lot of proofs to prove this belief; here we will summaries these
proofs in a few points.
One: Allah has said in his holy book '' verily we have sent down the
Reminder (the Qoran), and verily We (our self) unto it will certainly be the
guardian. (Al-Hijr:90)and a lot of other verses that promises its protection
and ''.Verily God fails not in(His) promise (al-ra'd:31).
Two. Since the very beginning of the revelation the holy Qoran was paid a
lot respect and attention. Not only the Muslims were attentive, the Holy
Prophet (peace be upon him and his progeny) excessively called and ordered
that the Qoran be memorized and written, and tenanted. From that time a lot
of people memorized the holy Qoran and some became'' writers of the
revelation'' protecting all the Qorans written. So with all this attention
it was close to impossible for the holy Qoran to be altered.
Three: An abundant amount of traditions from our holy infallibles mentioning
the impossibility of the Qoran being altered and denying any such accusation
shiites by following these holy sayings which are to many to be mentioned
believe that the glorious Qoran is for from being altered their scholars and
research are at the beginning of this belief.
For more historical, Qoranic, and traditional proof you may review to the
many sources written about this subject, even though unfortunately there are
not so many written or translated in the English language.
The Qur'an orders as well as refrains, remains silent and also speaks.
It is the proof of Allah before His creasion...(sermon183-Nahjul Balagha.)