The variances in the Bible you speak of don't change the central gospel message. It only gives people who want an excuse not to follow the truth. We know what has been added and taken away from the Bible because of the many undestroyed manuscripts in our possession. This is something that cannot be done with the Quran; so, you don't know what was falsified and even if one can prove there was no falsification which cannot be proved, there is no prove it is from our Creator especially when it goes so completely against the most important part of the Scriptures that came before.