An interesting take on the problem by an honest Christian professor (whose website The Biblical World is well worth a look at)
John Byron, Associate Professor of New Testament at Ashland Theological Seminary, writes
One of my standard lines that I tell my students is that we have virtually none of the original manuscripts of the New Testament. All that we have is copies of copies. This usually takes many of my students by surprise and for some it is a challenge to their faith. The biggest question they ask is, how do we know, then, that what we have in the New Testament is what the authors wrote?
And therein lies a debate. Can we, through the study of copies of copies, reconstruct the New Testament? Can we get even close? Some are confident that we can, others say no.
There are, of course, good people on both sides of the debate. Two people who have been debating this issue publicly recently are Bart Ehrman and Dan Wallace. Erhman is a prolific New Testament scholar and text critic who says “no.” Dan Wallace is also a New Testament scholar and text critic who says “yes.”
Professor John Byron comments on the debate:
Having watched this I must say that I am impressed with Bart’s driving question and points about the “original.” I don’t think Dan quite answers the question in a sufficient way. Having said that, it is clear that they arguing pass each other at some points.