We're coming to the home stretch on my series on why it is rational to believe that the Bible can be deemed trustworthy as a historical document. Obviously we could hold the Bible to be 100% accurate in matters of history and still not believe in God. For instance, one could accept that a man named Jesus walked this earth some 2,000 odd years ago, taught using parables, garnered a following, was crucified, and left an empty tomb without believing that man was raised from God or was the same God He claimed to be. That last step of faith, from believing the Bible accurately portrays what ancient folk believed about God and Jesus to believing the same thing as those ancient folk, is really a matter of further evidences and (most importantly) help from the Holy Spirit. Be that as it may, I still think that the Bible is a significant piece of history, as well as theology, and that its historical value helps understand better the theological value of the Bible as well.
Now the Bible appears to be a fairly complete view of a nation's history (OT) and in ancient terms, a very complete (and early) biography of a human individual (NT). If this is the case, we would hope that we would find historians and biographers outside the realm of Israel and early Christianity who could substantiate at least some of the Biblical texts. Finding such evidence would indicate that the Bible is not purely the work of biased or imaginative folks trying to build a new religion. In other words, finding extra-Biblical, non-Christian literature confirming some Biblical events adds credibility to the Bible's accuracy. This is something akin to the 'neutral' party witness in modern times: we tend to trust more those who have less at stake in a venture. Now this is not to say that the Bible could not be true if we didn't have extra-Biblical evidence; if nobody wrote anything mentioning me, and all future generations had to go on was this blog, it wouldn't mean the episodes from my life described herein did not happen. But, if someone were to verify the events, independently, it would add credibility to my account.
So, is there some of this 'third-party confirmation'? Indeed there is. For example, this site notes 24 examples of non-Biblical references to Jesus. This site offers more detailed citations. While some of these authors obviously disagree with the idea that Jesus was who He claimed to be, they all confirm He existed. Some confirm He was crucified, others that He had a large following who believed He as a healer, rabbi, Messiah. Certainly they affirm the first-century beliefs of the church, even though they didn't agree with those beliefs themselves.
I wouldn't expect non-Christians to accept that Jesus was God. But it is certainly compelling that they repeated the claims of Christians, and described the early Christian faith (and noted Jesus' crucifixion) despite not holding the same belief. Not a confirming proof, but certainly another step in credibility for the Biblical texts.