a proof of validity as we have demonstrated earlier. So there has to be a sound process of historical narration and passing on of knowledge that validates the honesty and credibility of the narrators and the sources, or else, anyone could alter or manipulate whatever way he wishes for whatever purpose he wishes! So as far as historiography is concerned, Christians cannot prove that those indeed are the words of the people to whom they are related. Much less can any followers of any other faith, other than the true faith.
On the other hand I can give a lot of evidence from the Quran and the words of well examined and validated narrators in the history of the Moslem nation, that it is indeed telling the truth, and that it is today the way it was fourteen centuries ago, without any dark holes in the first century, or the two centuries that follow. I can also demonstrate some of the many miracles of reason and knowledge it has proven to include.
No book could be true about its claim of a heavenly source, when it is easy to demonstrate with clear evidence, empirical and rational evidence, that it contradicts itself, or contradicts with established facts that are not subject to debate! Yes, a myth will always contradict with findings of science, and the true word of the true creator should never include any such myth! Can it be that the one who created the universe, failed to know that this or that bit of information is demonstrably and evidently wrong? This is impossible.
When a book or a story is simply the outcome of a limited human mind, and limited human knowledge, it is easy to prove that it is false; when it claims to answer questions about the deity! The faith that builds upon it will always be easily proven