I am willing to accept the argument that one shouldn't trust the bible as it has been changed so many times. There are many inconsistencies in the bible, but what if we had the original bible? What if we had access to the original texts, would we still need the Qur'an? I mean Why debate when all we need to do is go to the source of the text.
I assume that by the Bible you are referring to both of what are known today as the Old and New Testaments; in Islamic parlance these correspond to the Taurah and Injil respectively. According to the Qur'an, the Injil was meant to be a supplement to the Taurah, both confirming it and making lawful some of what the Torah had forbidden.
The Qur'an however abrogates the law of both the Taurah and Injil. In addition, while both the earlier revelations were meant for a particular people (the children of Israel) during a particular time period (between Moses (pbuh) and Muhammad (pbuh)), the Qur'an is the final revelation of God to all of mankind until the end of time. While the theology of all revelations (in their original form) is identical, as it must be to originate from the same source, the ritual laws differ.
Muslims believe that if we had the original forms of both the Taurah and Injil, they would in fact confirm the coming of a Messenger among the unlettered who would be the final Prophet, along with a number of unmistakable characteristics. Some of these descriptions survive in contemporary versions of the Bible. To answer your question, the original texts would directly imply that the Qur'an is the word of God applicable today.
In Islam we learn about the Original Bible and the corruption that happened to it by some of the Jewish and not good followers during the ages.
in the Original Bible and all previews religions a confirmation that Muhammad the Messenger of Islam will come and a specific Sign will lead the world to him. but after he came they refuses to follow him and hides the remaining of bible that talks about Islam and each christian have to declare to islam. Surah Assaf Explanation of Surah Assaf Conversation about this matter
When you look at the both The Bible and the Quran they are both supplements of the Torah and Veda the only difference between them is the names of the writers of the Verses in the original version of the Quran they were calling Jesus as the Anointing One and in the new version they call Jesus the Prophet of all mankind