Hmmm I haven’t personally investigated the type of quotations that are claimed. Unfortunately Barnett doesn’t give details as to which NT books are (supposedly) quoted by the various authors. Something for further research when I have time; of course there are other reasons to date the NT within the first century in addition to the church fathers … a quick search brought me to CARM’s article here:
http://www.carm.org/questions/written_after.htm
Note that I don’t think CARM is always the best (and there seems to be at least one typo, 79AD should be 70AD I think) but these articles seem decent. (Um at least when I skimmed them just now heh.)

Regarding Paul’s “according to”, I’m not sure why he uses different wording, but how does using “according to” imply it was not a historical event? The ESV translates this section “in accordance with the Scriptures” which seems like the most natural way to interpret it. Matthew was writing to a primarily Jewish audience whereas Paul’s audience would have been mostly Gentile, so I that might account for the different wording. I don’t know Greek, but another possibility is that using that word worked better here (in terms of meter, style) to make the creed easier to say/remember.

I have often heard it claimed that the early Christian apologists quoted from what was to be the New Testament (and some other documents as well); however, from what I’ve seen, the quotes are very fragmentary, and never refer to a document by name. For example, it is claimed that when Polycarp wrote the words “steadfast and immovable”, he was “quoting” from I Corinthians 15:58, which reads

Therefore, my dear brothers, stand firm. Let nothing move you. Always give yourselves fully to the work of the Lord, because you know that your labor in the Lord is not in vain.

There are many more examples of this, which casts doubt on the assertion that “Three authors who wrote at the turn of the century …all quote heavily from the New Testament.”

Regarding Paul, he was referring to the Old Testament. There are prophecies regarding the Jewish Messiah specifically or a savior more generally in the Old Testament, and so Paul (a Jew) would have been referring to these prophecies to essentially say “See, he did exactly what was prophesied.”

Agreed that Paul was referring to the Old Testament when speaking of “the Scriptures”, but the words “according to” seem rather incongruous if referring to a historical event. Why not “in fulfillment of”, like Matthew uses?

You’re right, it would have been more accurate to say “all quote heavily from the documents that would be included in the New Testament.”

Although the New Testament wasn’t formally and definitively decided until the 4th century, there’s remarkable agreement from the second century onward as to which books are included. In fact David Trobisch’s recent book on the development of the canon argues against the common notion that there was a long period of canon development:
http://rosetta.reltech.org/TC/vol06/Trobisch2001rev.html

But you’re right, the quotes themselves do not prove that the documents are the same as the ones we have now; they are only one piece of the cumulative case for the NT’s reliability. My intent with this post was to attempt to demonstrate the original writings were early and eyewitness testimony, not to argue a comprehensive case for their accuracy.

I have not and cannot verify this for myself (due to the obscene time it’d take) however it is often claimed that were all of the New Testament writings from the first few centuries lost, we could still reproduce almost the entire NT text from only using quotations in the the early church fathers.

In terms of which books are quoted by which early church authors, here’s Paul Barnett’s lists …

Clement: Matthew, Mark, Luke, Romans, 1 Corinthians, Ephesians, 1 Timothy, Titus, Hebrews, James, 1 Peter

Ignatius: Matthew, Mark, Luke, John, Acts, Romans, 1 Corinthians, 2 Corinthians, Galatians, Ephesians, Philippians, Colossians, 1 Thessalonians, 1 Timothy, 2 Timothy, Titus, Philemon, Hebrews, James, 1 Peter, 2 Peter, 1 John, 3 John, Revelation

Polycarp: Matthew, Mark, Luke, John, Acts, Romans, 1 Corinthians, 2 Corinthians, Galatians, Ephesians, Philippians, Colossians, 2 Thessalonians, 1 Timothy, 2 Timothy, Hebrews, 1 Peter, 1 John

Whew! Again, I don’t have the time or resources to verify this, but Barnett (who taught/teaches ancient history at Macquarie University in Sydney) is a known expert in this area.

Regarding Paul, he was referring to the Old Testament. There are prophecies regarding the Jewish Messiah specifically or a savior more generally in the Old Testament, and so Paul (a Jew) would have been referring to these prophecies to essentially say “See, he did exactly what was prophesied.”

That said, Paul wasn’t martyred until 63-68AD, so it’s at least possible he was familiar with some of the NT writings. In fact Paul’s writings themselves are referred to as Scripture by Peter (2 Peter 3:15-16) and there is a possible reference to Luke’s gospel by Paul in 1 Timothy 5:18 (though this last reference is rather debatable IMHO).

Long reply … I’m drained … hope this at least partially answers your questions!

Three authors who wrote at the turn of the century (Clement in about 96AD, Ignatius in about 108AD, and Polycarp in about 110AD) all quote heavily from the New Testament.

First of all, a minor quibble. The New Testament didn’t exist until the fourth century, so quite obviously, they couldn’t have been quoting from it. In any case, I would be very interested to know which gospels and/or epistles Clement, Ignatius and Polycarp quoted, and, specifically, the quotes themselves.

Also, quotes can indicate existence, but that doesn’t mean the entire corpus from which the quote came is the one we currently have. We know, for example, that many of the gospels were redacted over time. So, saying that such-and-such gospel was written before 96 CE doesn’t necessarily mean that it was the one we currently possess.

For what I received I passed on to you as of first importance: that Christ died for our sins according to the Scriptures, that he was buried, that he was raised on the third day according to the Scriptures…

It is interesting that Paul writes “…according to the Scriptures”. Since he obviously could not have meant any of the NT scriptures, what scriptures could Paul have been referring to? And why would Paul write that, if he were describing a historical event?