A Tidbit of Bible History:
The Bible is initially approached as any other ancient work.
It is not, at first, presumed to be inspired.
From textual criticism we are able to conclude that we have a text the accuracy of which is more certain than the accuracy of any other ancient work.
Next we take a look at what the Bible, considered merely as a history, tells us, focusing particularly on the New Testament, and more specifically the Gospels.
We examine the account contained therein of Jesus’ life, death, and resurrection. Using what is in the Gospels themselves and what we find in extra-biblical writings from the early centuries,
We then take that and together with what we know of human nature (and what we can otherwise, from natural reason alone, know of divine nature), we conclude that either Jesus was just what he claimed to be—God—or he was crazy.
Further, Christ said he would found a Church. Both the Bible (still taken as merely a historical book, not yet as an inspired one) and other ancient works attest to the fact that Christ established a Church with the rudiments of what we see in the Catholic Church today—papacy, hierarchy, priesthood, sacraments, teaching authority, and, as a consequence of the last, infallibility.
Christ’s Church, to do what he said it would do, had to have the character of doctrinal infallibility.
We have thus taken purely historical material and concluded that a Church exists, namely, the Catholic Church, which is divinely protected against teaching doctrinal error. Now we are at the last premise of the argument.
This Catholic Church tells us the
(3)Bible is inspired, and we can take the Church’s word for it precisely because the
(2)Church is infallible.
(1) because she has the same authority as Christ
Only after having been told by a properly constituted authority—
(1)that is, one established by God
(2)to assure us of the truth concerning matters of faith and morals—
(3)that the Bible is inspired can we reasonably begin to use it as an inspired book.
I took most of the information from catholic.com/library/Proving_Inspiration.asp , and reformatted for the sake of simplicity.