Ask the Atheist

I suppose this isn't the best place to ask this question, since it's more historical in nature, but I haven't been able to find any relevant "Ask the Historian" sites, and I trust you guys more than "Ask the Theologian." So here goes...

I've been reading about the history of the New Testament's formation for some time now, and especially about the "Four-Source Hypothesis." For other readers, this is a theory proposed by New Testament historians that the authors of Matthew and Luke used Mark as a "source," that is, they copied stories and sayings of Jesus word-for-word from Mark (as well as three other sources, but my question doesn't concern them). There's simply no other way to account for the word-for-word agreements. If Mark, Matthew, and Luke were writing independently of one another, there's no way they would have described the same event in precisely the same words. (For a variety of reasons, most historians agree that Mark was first, and Matthew and Luke copied stories from Mark).

So here's my question: Why would anyone compose a document in such a peculiar manner? Why would Matthew and Luke take huge sections of Mark and cut and paste them word for word into their own Gospel? Why wouldn't they just paraphrase Mark, or use completely different words to describe the same event, as would seem more natural (except when quoting Jesus)? I know that plagiarism as we know it didn't exist in the ancient world, and that Matthew and Luke often did make lots of little editorial changes to Mark's text. That's not what my question is about. My question is, Why would anyone use their sources in such a strange way? If I sat down to write a history of the Roman Empire, I would not cut and paste huge sections word for word from The History of the Decline and Fall of the Roman Empire, no matter how important I thought it was. So why did the Gospel writers (as well as Old Testament writers) do this? Was it a common practice in the ancient world? Are there any secular texts from antiquity that use sources in this same way? (Examples?!)

To my eternal frustration, no history of the New Testament I've read seems interested in this very basic question. So, plagued by this issue, I've tried to come up with some plausible answers of my own. Please let me know if any of them are on the mark or total bunk:
1. Matthew and Luke copied from Mark simply for convenience's sake. They were kind of lazy: it was easier to copy than trying to reword it all.
2. Related to the first reason: Learning to write in the ancient world was a lot more difficult, and it would have taken an inordinate amount of work to compose an entirely new document, so Matthew and Luke kept Mark's exact wording when it wasn't objectionable, to save time and money (for paying scribes).
3. The Gospel of Mark was highly revered as inspired and authentic by Matthew and Luke, even if it needed tweaking, and so, out of deference, they preserved the original wording, except when it was objectionable theologically.
4. Matthew and Luke's church communities really liked the Gospel of Mark, so they kept the wording as similar as was theologically possible, so that their new Gospels would find favor with their communities, and perhaps one day replace Mark.
5. Related to #4: Matthew and Luke's communities were all very familiar with Mark, and Matthew and Luke couldn't have changed much without exciting protest from their communities.
6. Matthew and Luke's communities were not at all familiar with Mark, and so Matthew and Luke wanted to introduce it to them, with some changes.
7. Matthew and Luke's communities were not at all familiar with Mark, and so Matthew and Luke wanted to take undeserved credit for some of Mark's more brilliant passages.
8. Matthew and Luke believed that Mark was based on an even earlier written source, and they wanted to stay as faithful to this original as possible, while still emphasizing somewhat different theologies.
9. Cutting and pasting sources was common in the ancient world for reasons totally unrelated to the writing of these Gospels, and Matthew and Luke were just unthinkingly following common practice.

Now, some of these ideas may sound plausible, but remember that I just pulled them out of my ass. I've never read anything by an NT historian that indicated that any of the above 9 reasons are valid. And that list should show you how much thought I've given to this question. So if you can't answer my question, or if you think it's not appropriate for this site, could you please direct me to a history book that deals with this question, or a decent "Ask the Historian" site? Thank you for your time, and keep up the good work!

-Leon

P.S. I just thought of a way to make this question vaguely relate to atheism. The first 2 chapters of Genesis contradict each other a lot, and the reason usually given is that a later editor pasted together two creation stories. So why would he do this, and why wouldn't he paper over the obvious contradictions? This kind of reasoning might be used by a Christian trying to argue that Genesis 1 & 2 do not contradict each other, and that there must be some way of reconciling them that we don't see.

I'm not sure what you mean when you say "word for word", but I'm going to assume that you've noticed that the exact same words are used in the three gospels in some areas. I don't agree with that, but maybe I wasn't paying attention. (Also, for you guys saying they were comparing notes, their resurrection stories are a little different, BUT NOT contradictory)
I'm going to give you the answer that they copied "word for word", because, yes, to them it was very important. You did say that "I would not cut and paste huge sections word for word from The History of the Decline and Fall of the Roman Empire, no matter how important I thought it was.", but it doesn't mean that these guys can't just cause you wouldn't. Any sort of paraphrasing would increase the chance for a disagreement of text, which you - (seriously, what do I call you? It's like if I say atheist, some people get all worked up, I say skeptic, heck I'm a skeptic, if I say "non-Christian", you might just be a confused one, whatever! So I'll just say "-") always seem to try to find. (http://askanatheist.wordpress.com/2008/12/06/
bible-contradictions/) I've answered most of these, but I need to explain the fowl and Paul one, but my school blocks those pages, for some, odd, reason...

And please give me your "Genesis complications", if you're up for it.