For a lot of Christians the Bible and all of its contents are 100% true and factual whether spiritually or historically. Not all Christians hold the Bible to be inerrant and infallible while also reading it in a literal context, but for these Christians it is a foundation stone to their faith. If the texts were not inerrant and infallible then the inspired writers might not have been directly inspired by the Holy Spirit which ends up challenging their view of God. For their understanding of God to be correct everyone and everything along the line of transmission must also be inerrant and infallible: prophets, inspired writers, apostles, scribes, and all those who participated in the canonization of the Bible.
[Isaiah's Lips Anointed with Fire by Benjamin West]
The Divine-->Prophet--> First listeners of the revelation--> Storytellers spread by word of mouth (tradition)--> first copy of text--> 2nd generation copy of text, 3rd, 4th etc--> canonization--> more copies--> more interpretations,etc-->modern day text
This is a very rough line of transmission but at each point there is huge room for error. It is Man's mortal nature that limits our sense of reality, and when our limited nature comes in contact with the Divine we fail at fully grasping the revelation. It's not that God can not "dumb down" the message for us to understand but that as humans we repeatedly fail in accepting and implementing the messages (one reason I believe why God feels the need to send so many prophets). At that very moment when the revelation is in the hands of one Man (or woman) how do we know that he got it right or even if it was a revelation at all? This is one reason I can't prove or disprove what Buddha, Muhammad, Baha'ullah, or even Joseph Smith may have experienced. You have to take the word of a potentially fallible man delivering the infallible to the world. When that message is first passed down from Prophet to the first listeners each one of them interprets it differently. As the message passed down from generation to generation those that sought its preservation copied them down in writing. Although the texts preserve the message it takes some of the emotion, spirit, and life of the original revelation as told through the storytellers. As generations pass the texts become distorted and twisted. Some scribes, with good intentions, find what they believe to be "errors" and have them properly corrected by their personal interpretation and not that of the prophets'. Two millennia of recopying and reinterpreting the texts have generated thousands of denominations, beliefs, and ideas under the umbrella of Christianity.
So how do we unearth the original revelations without being lost in Man's own interpretations? I believe this is only possible if one were to experience the divine for oneself. Some may call this innate knowledge, Nirvana, a personal relationship with Jesus Christ, Moksha, an out of body experience, there are dozens of words that attempt to describe an experience that is indescribable. The trouble with prophets is not that they've failed to convey the message as the Divine intended but that the message can not be truly passed on without experiencing it yourself making it understandable to those receiving it. It's like trying to send someone a parcel of water in the mail.
"It's impossible to wrap and tie a pound of water in a paper package. There are kinds of paper which won't disintegrate when wet, but the trouble is to get the water itself into any manageable shape, and to tie the string without bursting the bundle." (Quote from The Wisdom of Insecurity by Alan Watts)To make it understandable to those that have not experienced the Divine one must adapt the message. Jesus did just this by using parables. He could only tell people what the Kingdom of Heaven is like and not exactly what it is. Truly connecting with God is to first understand that each religion is offering their own interpretation of the Divine (their pound of water wrapped in paper). We can spend years debating which interpretation is correct or we can open our hearts to God and to one another and begin to experience it for ourselves. If we each have the potential and the choice to connect with the Divine then who's to say that what we each experience is not real? If it's just you and God how can anyone else dictate and shape the terms of your relationship? One of my favorite Bible verses illustrates what should guide us on our search for the Divine.
Philippians 4:8-9 (NIV)
8Finally, brothers, whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable—if anything is excellent or praiseworthy—think about such things. 9Whatever you have learned or received or heard from me, or seen in me—put it into practice. And the God of peace will be with you.