There is one proof of the Holy Qur'an that cannot be dismissed. And it is is as follows:
A man, from the sandhills of Arabia, one of the most ignorant areas of the world at the time, declares that he is a Prophet of God. He is unlettered and has never formally been taught anything. His first order of business is to tell the world that he is a prophet from God, and that there is only one God. And all polytheists are false. Not only that, he declares the Jews and Christians to be false as well.
In one fell swoop, he has turned the entire world against him. The idolators declare he should be killed, the Jews and Christians declare him a heretic. Friends turn to foes. And he his left alone with only a handful of followers. He declares not only that everyone else is false in their beliefs, but that they are faithless, hellbound if they don't reform, ignorant, and their fathers of old were also as ignorant as they are.
Instead of building relations, he is breaking every avenue of his worldly success.
He then declares that God has promised him victory over all his opponents. He dumbfounds all philosophers and clergymen with undeniable arguments from the revelation he is given. He declares that the kings of the world will be conquered when they oppose his message. So, 1 man vs. the entire known world. He sticks to his message, and changes not one iota to reform to the beliefs of the society. He declares that God will grant him all prominence and grandeur, and that all his enemies will be humiliated.
And the crazy thing is, that it happens. It's like someone from the middle of the Amazon jungle, not having one day of schooling, declaring that he will conquer the U.S and Russia, that his greatness will be shown to the world and everyone else humiliated and he somehow manages it. And he declares all this when he has not even enough followers to count on the tips of his fingers.
This is the beauty of Prophecy in the Qur'an. Other scriptures only describe things like earthquakes and pestilence will happen, which anyone can predict. But who can predict their own victory and the humiliation of all their opposers within their own lifetime? And that such a thing also comes true?
At the very least, it demands that any serious seeker of truth look into the rest of the claims of the holy Qur'an. In regards to prophecy, there doesn't seem to be any grander sort of prophecy that can be shown by God in support of a prophet of his.