Here’s the full outline of the process:
We begin by treating the Bible not as an inspired text but simply as any other historical text such as the works of Homer or the accounts of war by Julius Caesar.
Using textual criticism, we are able to conclude that today, 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, still considered merely as a historical text, 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, together with what we know of human nature (and what we can otherwise, from natural reason alone, know of divine nature), we conclude that Jesus was either:
a. a liar,
b. a lunatic,
c. or Lord (that is, just what he claimed to be—God).
The one thing we know he could not have been was merely a good man who was not God, since no merely good man would make the claims he made.
We are able to eliminate the possibility of his being a madman not just from what he said but from what his followers did after his death. Many critics of the Gospel accounts of the resurrection claim that Christ did not truly rise, that his followers took his body from the tomb and then proclaimed him risen from the dead. According to these critics, the resurrection was nothing more than a hoax. Devising a hoax to glorify a friend and mentor is one thing, but you do not find people dying for a hoax, at least not one from which they derive no benefit. Certainly if Christ had not risen, his disciples would not have died horrible deaths affirming the reality and truth of the resurrection. The result of this line of reasoning is that we must conclude that Jesus indeed rose from the dead. Consequently, his claims concerning himself—including his claim to be God—have credibility. He meant what he said and did what he said he would do.
The Bible, still only considered to be historically accurate book, records that Jesus, who is God, said he would found a Church. Both the Bible and other ancient works attest to the fact that Jesus established a Church with the rudiments of what we see in the Catholic Church today—papacy, hierarchy, priesthood, sacraments, and teaching authority.
Thus, beginning with the historical data alone, we conclude that Jesus founded the Catholic Church. Because of his Resurrection we have reason to take seriously his claims concerning the Church, including its authority to teach in his name. Teaching in His name and with His authority requires infallibility, and that, too, is evident from the recorded teachings of Jesus.
The infallible Catholic Church tells us the Bible is inspired.
Only after having been told by a properly constituted authority—that is, one established by God to assure us of the truth concerning matters of faith—that the Bible is inspired can we reasonably begin to use it as an inspired book.
So, the historically accurate Bible tells us that God founded a Church authorized to teach in His name. Since logic dictates that such a Church cannot teach error while doing so, we accept the Church’s infallible judgment that the Bible is not only historically reliable but also inspired.