RE:"It does not matter what the bible claims it is,"
When someone is on trial for some sort of crime, their own testimony is still considered evidence. They don't just prevent the accused from testifying on their own behalf, but rather they let them speak and then they weigh all of the evidence. You might do well to look into Simon Greenleaf's legal examination of the Gospels, because the Bible does carry some weight for it's reliability within itself: http://archive.org/details/examinationoftes00greerich
Greenleaf was a legal authority who wrote the books that were used by courts on how to determine evidence: http://www.amazon.com/Treatise-Law-Evidence-Simon-Greenleaf/...
It's notable that he was not a Christian when he began to apply his legal rules to the Bible, but became one as a result of his examination of the evidence.
RE:"you cannot start with the assumption that it is TRUE"
In presuppositional apologetics, it's thought that everyone starts with the presupposition of their own worldview, that there is no neutrality, and that the way to determine which view is correct or incorrect is to show which worldviews are internally consistent or inconsistent with reality. So they would argue that everyone starts out with their own assumptions.