to prove that God did protect his Words, is because first of all the quran's original manuscripts are present not a word has been changed.
second, not a single verse of the quran has been proved wrong.
islam for a long time has been interpreted wrong.
As the christian preacher Skip Estes said when he was small or was growing up he taught that muslims were terrorists and that they didnt believe in God and ridiculous stuff like that.
40 or something years later he became muslim and same with his father.
right now theres like a crazy incline in islam.
its like a tradition now, who ever goes to jail comes back out muslim.
SubhanAllah.
As the Quran says, "When truth is hurled against falsehood, falsehood perishes, for falsehood by its nature is bound to perish."
Salaam.