Well, if the Bible could be proven 100% true, then it wouldn't be Faith. But, since we rely on Faith in our..........Faith, then we must trust that the Bible is in fact, 100% the word of God. As for being unaltered, I believe that everything that God was saying is accurately portrayed. As for the exact words, it can't be the same. If you've ever done any translating, you know that languages don't translate straight across. It is also important to realize that many terms used in the Bible are unknown to us. For example, we don't know exactly what length a "Cubit" represents, as described in Genesis. As for proof of the accuracy from the original texts to our modern Bible, they have virtually not changed. I don't know any links, but I have read and heard this from what I consider to be reliable sources. I know that argument doesn't hold weight, but I also have no reason to lie.
God bless
Rejectreality has made some good points. I'd like to add to it in another way it was presented to me...
1. Look at the style and how the entire Bible was written. It is not a "Once upon a time" format. It is written "matter-of-factly". It offers specific information about instances of the past.
2. The Bible talks about real places that have existed in the past, and that exist today. Archaeologists have used the Bible to find hidden cities. Those who find them, even today, are amazed at how accurate the Bible's descriptions are of places that have been lost and hidden for centuries.
3. The Bible talks about real people. There are ancient manuscripts and artifacts testifying of people that are in the Bible, like king Nebuchanezzer (?), king David, Pontius Pilate, etc.. I even read in a newspaper article of a fairly recent archaelogical artifact with an inscription referring to the city of David. Prior to that, his existence remained in doubt.
4. The bible has approximately 5,000 prophecies, many of which have already come to past. Others are being fulfilled today. Some are yet to come, but are showing signs of being fulfilled.
5. The Bible contains 66 books written by 44(?) authors, which covers a span of around 4,300 years. Many of the authors lived hundreds and hundreds of years apart. Yet, their testimony of what God said and done remain incredibly consistent with each other. We can't even be consistent with our parent's generation. Yet these people have done it.
6. The God I worship is in the Bible, and through his name, I cast out devils, healed the sick, speak in tongues, etc. No other book in the world can testify of God and give me His word and the knowledge of Him to do these things. If the Bible did not accurately portray God, then I would not be able to do any of these things.
7. Have you ever read the New York's Best Seller, "The Bible Code"? It's a fascinating book describing how incredibly awesome the Bible is, and how only God himself could have orchestrated it.