I enjoyed watching The Case for Christ, a film adaption of the bestselling book by Lee Strobel. However, I did notice one significant error. In an interview with an archaeologist turned priest, the following dialogue occurs:
Strobel: I understand that a number of people claim to have seen Jesus after his crucifixion, and some of them even wrote it down. But ... how can we be sure of the reliability of those manuscripts?
Priest: Well, the same way we authenticate any historical document. By comparing and contrasting the copies that have been recovered. It's called textual criticism. The more copies we have, the better that we can cross-reference and figure out if what the original was saying is historically accurate. And the earlier they come from in history, the better.
Here the priest has confused two completely independent issues. The priest is correct in his later assertion that textual critics have been able to reconstruct the original wording of the New Testament with a high degree of confidence. In other words, textual critics have been able to identify and eliminate changes made by scribes (see my video on that topic here). However, the use of textual criticism to establish the original wording of a document does absolutely nothing to establish the historical accuracy of the claims made in that document.
For example, textual criticism could be applied to one of the many romance novels from antiquity. In this case, the textual critic would compare the surviving copies of the novel in order to determine the original wording. However, establishing the original wording of the novel does nothing to change the fact that the novel is a fiction.
Now of course there are means of assessing the general historical reliability of an ancient document, but all such methods fall outside of the realm of textual criticism.
(For more on the historical reliability of the Gospels, check out the lectures on my "Big Questions" page here.)