PhysicsGirl, if you get back into the argument, er, discussion, with your friend, keep in mind a few of the arguments that are often made that can be pretty hard to refute unless you know a few things. One of these arguments it the so-called "Manuscript Evidence" in which proponents of the Unchanged Holy Word of God will make a claim that is basically true--sort of. They often say that there are at least 5,000 manuscripts of the New Testament in the Greek language, and these 5,000 are all in very close agreement on the text, and that the variances do not alter the basic theological message. This is true. It is also irrelevant.

Why? Because almost every one of those manuscripts were produced centuries after the time of Christ and the apostles. In fact there are no complete copies of the New Testament that were produced before the 4th century, after the reign of Constantine--Codex Vaticanus and Codex Sinaiticus. Google either of those and you'll get enough material to keep you busy for the rest of the evening.

What really matters regarding manuscripts are, what copies exist that were produced in the first century? None. Now there's one tiny fragment of a page from the gospel of John, about the size of a postage stamp, that might have been produced in the first century, but most likely it was copied from the 2nd century. And, there are very very few other manuscripts that are anywhere near as old.

So if your friend makes this claim about the thousands of manuscripts, ask them how many of them have been reliably dated to earlier than the 4th century. He or she probably won't have any idea, and if they don't, encourage them to find out.