This is an important question for two reasons. One, the number and distribution of manuscripts of the New Testament is a key issue related to textual criticism. Often times, students will approach me from the perspective “manuscript A says this; and manuscript B says something else; therefore we do not know what Paul or Jesus said at that point.” That would be true if you only had two manuscripts. If there were only two manuscripts of Matthew, and one had Jesus say “kingdom of Heaven” and the other had him say “kingdom of God,” then you might conclude that we do not know what Jesus actually said. But we have more than two. We have somewhere in the neighborhood of about 5,500 manuscripts of the New Testament. If we broaden that to include lectionaries, which is the Bible arranged in the order they were read in the ancient church rather than in canonical order, then the number grows dramatically. In fact, I have even heard one scholar recently say that if we include all the citations of the early church fathers quoting from the scriptures in sermons and writings then the number could be as high as even 1,000,000 manuscripts. But 5,500 to 5,700 is about how many we have. If you have 5,500 manuscripts of the New Testament from all over the world, that fall into families, and have readings, then you do not really have the luxury of saying “two manuscripts say different things, so we do not know what was really said.” That is not the case. We do know what Paul or Jesus wrote – he wrote one of these two things. And in the vast majority of cases, the difference between manuscript A and manuscript B is pretty insignificant. Textual critics pay attention to the differences; but in terms of what Paul’s message was, or what Jesus really said, it is not a big issue at all.
In addition to the sheer number of manuscripts, it is important to know how that number compares to those of other ancient works. If you look at various critical editions of works such as The Iliad, Caesar’s Gallic War, and Beowulf, you find that there is not anything even remotely close to our number of New Testament manuscripts. We think about this in two categories. First, how many witnesses do we have? Secondly, how close to the time of the original writing are those witnesses? For example, there are about 650 copies of The Iliad in existence. That seems like a lot, and is enough to produce critical editions. But when you compare that to the volume of manuscripts we have of the New Testament, it is a small number. Caesar’s Gallic War is usually considered to be fairly historically reliable; but as far as I can tell, there are only about one dozen copies of it in existence. The earliest of those copies is probably a thousand years after the event. Again, that is not the case with the New Testament. In fact, we find that many of those New Testament manuscripts – the ones we consider to be most reliable – are among the most ancient. We have complete copies of the New Testament in the 4th Century. Codex Sinaiticus and Codex Vaticanus probably date to the mid-4th Century. But there are manuscripts even earlier than that. There are manuscripts that go back to the 2nd and 3rd Centuries. We have a manuscript that is called P75 that is very similar to the text of Vaticanus, yet it was not copied from it. It is 200 years older. These ancient papyri have survived in part because of the climate in which they were preserved. We have manuscripts that go back to within 100 years of the events, and within decades of the lifetimes of the eyewitnesses. There is also a manuscript that is designated as P52 that is dated by some scholars as early as 125 AD (give or take 25 years). P52 is a fragment of the gospel of John and was found in a library in Egypt, which pushes the date for the writing of John back. In addition, because it is pretty universally agreed that the Synoptic Gospels were written prior to John, P52 also pushes the date for the writing of the synoptics back into the lifetime of the eyewitnesses. There is no ancient work that can boast anything close to that. There are only 2 or 3 copies of Tacitus’ Histories and Annals of ancient Rome, and they are medieval manuscripts. As far as I know, there is only one copy of Beowulf in existence.
In contrast, with the New Testament, you have a widely distributed number of manuscripts from all over the world from Byzantium and Caesarea and from the West and from North Africa. You have the New Testament very quickly translated into languages like Latin and Coptic and Syriac. The manuscripts are all over the world and have an entirely uniform message with a fairly uniform text to the point where the differences are significant to scholars, but not significant to interpreting meaning. If you have a New Testament manuscript from Byzantium and a New Testament manuscript from North Africa, you are not going to compare those two and wonder what the author actually said. You might have some questions about the long ending of Mark or the woman caught in adultery, but the geographical distribution and the distribution of age, give great credibility to the transmission of the New Testament into the modern day.