We cannot verify any details of the life of Alexander the Great. Nothing about him that is in textbooks today can be trusted, since his earliest biographers came centuries after his death.
Homer's Iliad, may not even be by Homer, in fact it probably wasn't. If it was by Homer, then those after him probably changed things to improve the text until the final version settled down around 1,000 years after its supposed writing.
The recorded history of the Roman Empire cannot be viewed as fact because those recording the history were part of the Roman government, giving them a pro-Roman bias, which makes every thing they say untrustworthy.
Basically every document from antiquity is worthless as far as history goes. They may be nice stories, but they can give us no fact as far as history goes.
In fact, we can only trust those things that have happened within the last few decades because by now legend may have crept into what we know and those events and people are hopelessly intermingled with fantasy and opinion.
This is the view that one would have to hold in order to be consistent, if you said the New Testament accounts of Jesus' life are not a reliable source of history.
Take Alexander for instance. The two earliest biographies we have of Alexander the Great were written by Arrian and Plutarch more than 400 years after his death in 323 B.C., yet historians consider these works to be generally trustworthy accounts of the life of Alexander. Legend did, in fact, make its way into stories about Alexander, but this took place in the centuries after these original biographies. Contrast that with the biographies of Jesus that we have in the New Testament in the form of the Gospels of Matthew, Mark, Luke and John. Even liberal scholars hold that Mark was written in the 70's (40 years after Jesus' death), Matthew and Luke in the 80's (50 years later) and John in the 90's (60 years later). (Many believe, and have evidence to support, earlier dating for the Gospels, but we will go with the outer edge dating for arguments sake.)
Those dates put every Gospel well with in the standard applied to other works of antiquity as far as time proximity that could lead to legend. Yet many scholars place a much higher burden of proof on the New Testament. 400 years is acceptable for Alexander, but 40 years is not acceptable for Jesus. This also does not take into account the information we can glean from Paul's letters that were written in the 50's (20 years later). We also find early Church creeds that Paul incorporated into his writings. The creed that Paul quotes in 1 Corinthians 15 can be dated even earlier. The crucifixion was around A.D. 30. Paul's conversion was around two years later. His first meeting with the apostles would have been around three years after his conversion. At some point during his meeting with the apostles, Paul was given this creed - meaning that we have information dating back to within 5 years of the crucifixion that speak of Jesus' death for our sins, His resurrection and a list of those Jesus appeared to after His resurrection.
Many contend that the Gospels have been changed over the years by different editors and supporters of Christianity. The New Testament has more manuscripts than any other work of antiquity. Second place is not even close. We have over 5,000 manuscripts that have been catalogued, by contrast the Iliad, written about 800 B.C. has fewer than 650 and come from the second and third century A.D. and following. We have portions of the Gospel of John that date at least 150 A.D., less than 100 years after the original.
As far as changes over the years, the New Testament again stands far beyond any other work. According to scholars Norman Geisler and William Nix, today we have a 99.5% pure document, with no doctrinal compromises. The variations between manuscripts are minor and insignificant. They pose no danger to any Christian doctrine.
Many critics of the Gospels claim that because of the personal nature of the apostles' relationship with Jesus, the Gospels are full of the biases of the writers. While the potential may be there for someone to embellish to enhance the reputation of someone. The case may also be that the writers so honor and respect the person they are writing about that they make every effort to record their life with integrity, in that way showing their love for that person.
Besides, what would the apostles have to gain from writing books that claimed Jesus was God? We must think back to their time, when both the Roman government and the Jewish leaders wanted to squelch any movement outside of the already organized religions. All the first Christian leaders had to gain was criticism, ostracism and martyrdom. They would certainly have no hope of monetary gain. If anything, the pressure would have been to keep quiet, to downplay Jesus' significance, to even forget they ever met Him. If they were embellishing details, it would have been advantageous of them to enhance their own image, yet we find countless cases in the Gospels of the apostles making mistakes and misunderstanding Jesus. We even have the case of Peter denying Jesus three times, why would they record this unless they wanted to be accurate?
Also, if the Gospels were unfaithful to the actual events, they were written well within the lifetimes of people who personally witnessed the events. Anyone could have stood up and said, "They got this wrong." This would have basically destroyed the Christian faith, since to join in those days meant you had to risk your life. Why would someone join a movement that might lead to your death if you knew it was based on a lie? Even further why would the disciples suffer the way they did for their faith, if they knew the things recorded in the Gospels were false? Why would they give their lives for something they made up? The old quote goes: Some people will give their lives for the truth, some may even give their lives for a lie they believe to be true, but no one will give their live for something they know to be a lie.
Why is all of this important? Because it returns us to C.S. Lewis ultimatum - Jesus was either liar, lunatic or Lord. If the New Testament is trustworthy, which it is when compared with any other work of antiquity, then the words of Jesus must be taken at face value. We are forced to choose what to believe about a man who claimed to be God, not a god or god-like, but the God. Claiming to be God does not make one a "good moral teacher." It presents us with our final choice, one we must make.
Information provided by The Case For Christ by Lee Strobel
Update: Since Louis raised the subject of the inerrancy of Scripture, I decided to add these links. My post was not intended to deal with that topic but luckily, Tim Challies has a three part series here, here and here on inerrancy, what it really means and dealing with the main objections to the doctrine.