The final objection to Christianity that Keller discusses is the belief that "You can't take the Bible literally."
This chapter is jam-packed, but I will briefly mention a few of Keller's arguments for the validity of the Bible.
"The content is far too counterproductive for the gospels to be legends."
If the New Testament gospels (Matthew, Mark, Luke and John) were just books written by some misguided Jews looking too hard for a Savior, then why would they include so much content that would be very culturally counter-productive to the advancement of their "new religion?" For example, if they were making up legend and promoting a false reality, why would they say that women were the first eyewitnesses and testifiers to the resurrection of Jesus - the leader of their "new faith?" A woman's testimony was not allowed in court at that time, so why not at least say that some men were the first to witness the risen Christ?
"The literary form of the gospels is too detailed to be legend."
C.S. Lewis, a renowned literary critic and former atheist recognized that the literary form of the New Testament gospels was incredibly distinct from any other form of fiction written during the first century. Instead, it resembles a form of first-hand account reportage - not legend. The gospel accounts record details (e.g. numbers, facial expressions, sleeping quarters) that were not consistent with the fiction of its day.
"Don't immediately assume that the Bible can't be trusted culturally."
Keller suggests that a reader consider that their problems with some texts might be based on an unexamined belief in the superiority of their current historical moment over all others. To reject the Bible as regressive is to assume that you have arrived. Also, Keller suggests that the reader consider that bothersome passages may not be teaching what it appears to be saying. For example, slaves in the first century were treated much differently than the New World slaves that we now think of when reading about "slaves." Keller is not condoning slavery, but merely pointing out that we a culturally conditioned paradigm that may not be consistent (and often is not) with the contemporary reader of the gospels. We should enter the Scriptures carefully, in community and with an open mind to the possibility that God's ways may in fact be higher than our ways!