After reading some of the claims listed on the site you linked to, I can conclude that there is an element of misinformation behind the content. And because there is so much of it, it would be unfair to expect me to sift through the material and provide a rebuttal for each claim. So I will direct you to a book called The History of the Qur'anic Text from Revelation to Compilation which, if you sincerely desire the truth, should answer your question.
If the Qur'an has never been altered, what about all the claims that it has listed here: http://www.answering-islam.org/Quran/Text/
The Muslim Perspective
Can god make a rock so big he can't lift it?
Answers: Muslim, Atheist, Christian
Aren't Allah, Brahman and Yahweh just different names for the same God?
Answers: Atheist, Muslim, Christian
What religions could possibly be true, given an atheistic and naturalistic worldview?
You say past time can't be infinite or we would never get to the present. Isn't that just Zeno's Paradox?
What happens to people who don't accept what you claim?
Answers: Atheist, Christian
Muslim Islam Fazlur Rahman Muslim Islam in Contemporary World Asghar Ali Engineer Muslim Islam vs. Islamism: The Dilemma of the Muslim World Asghar Ali Engineer Muslim Islam: Religion, History, and Civilization Seyyed Hossein Nasr Muslim The Prophet of Non-Violence: Spirit of Peace, Compassion & Universality in Islam Asghar Ali Engineer Muslim A Living Faith: My Quest for Peace, Harmony and Social Change Asghar Ali Engineer Muslim Islam: Misgivings and History Asghar Ali Engineer Muslim On Developing Theology of Peace in Islam Asghar Ali Engineer