score:9
Given the clarification of the question, an entirely new answer is in order.
The quick answer is that most of the rest of the NT
The dates of the New Testament books can be found in this question.
The entire Pauline corpus (Romans - Philemon), if authored by Paul, predates the Gospels.
Paul was executed in either 62, 65, or 68 AD, and all of this excludes John (95), Matthew (post-70), and Luke.
Mark may have been been written prior to Paul's execution, but even given the earliest date for Mark and the latest for Paul's execution would have given only 10 years. In any event, many eyewitnesses to the Resurrection were still alive at this point, and so Mark would have just been one more eyewitness.
The closest one could come to making a case for Scriptural recognition of Mark would be Paul's use of the Eucharistic formula, "Take, eat, this is my body," but again there, the question remains whether this was simply eyewitness account or drawing from the book. Most scholars believe it to be background knowledge of the account, rather than Paul having read Mark's account. (For that matter, Paul probably learned about it directly from Peter (Galatians 1:18), who is often seen as Mark's source!)
Additionally, James and Hebrews pretty clearly pre-date the Gospels, so again, no.
Acts, which chronicles the life of Paul, was written by Luke, and is clearly the second half of Luke-Acts.
When Luke begins Acts, he speaks of his own Gospel as "my former book". As such, Luke, when writing Acts, probably was unaware of his own inspired status, but he surely believed what he wrote to be an accurate account of the life of Jesus.
The only candidates for NT books after the "Synoptic Gospels" (Matthew, Mark, Luke) are the Johannine (1, 2, 3d John) books and the Petrine Books (1 & 2 Peter, and Jude which clearly borrows heavily from 2 Peter)
Of these,
John, if it is the same same, did author his own Gospel, and so again, we have the "are you aware of your own Scriptural status" problem. If it is a different John, the author is still closely indebted to John the Apostle, and so would have considered the John the source, not the Gospel.
Peter, if written by the Apostle Peter (and yes, some doubt whether or not both books were written by Peter), would have had the same status of John. John was an eyewitness, Peter was an eyewitness. Peter would have been more influenced by what he saw than what he wrote. Furthermore, Peter is most commonly ascribed the source of Mark's Gospel, so again, his own self-awareness in regards to inspiration is doubtful.
What may be most useful in answering your question is what Polycarp - a Christian matryr who died in 150AD, thought. He considered Matthew, Mark, and Luke to be Scripture, along with Acts, the Pauline, and Johnanine corpuses. Polycarp was a contemporary of John the Apostle, the last of the Apostoles to die. He's about as early a figure as you are going to get, and he's already really close to the actual writing. My guess is that he didn't include John in his recommendation list, either because he was so closely associated or it was really too recent.
Finally,
Remember that one of the classic marks of NT canonicity was apostolic claim to authorship. In other words, every one of the books was, at one time or another, considered to have been written by an apostolic eyewitness of Christ. This means all the works of the NT would have been written
tl;dr> No, the authors of the epistles didn't see the Gospel books as Scripture - they considered the eyewitness accounts as Scripture. Most of the books you are talking about were authored before the Gospels, but while many of the eyewitnesses were still alive.
Upvote:1
At least Luke was considered Scripture by Paul. 1 Timothy 5:18:
For the Scripture says, “Do not muzzle the ox while it is treading out the grain,”[a] and “The worker deserves his wages.”[b]
Here Paul clearly calls both Deuteronomy and Luke, "Scripture".
The Gospel of John was likely written after Paul's letters, and so is not commented on. But Matthew and Mark share a lot of common texts with Luke, so if they were known by Paul it is likely they also would have been considered Scripture.
Upvote:2
In the 2nd. cent. the Gospels were not classified as scripture. "Scripture" when mentioned in the NT, meant the Hebrew Torah and prophets. The phrase New Testament comes from the Gnostic Church(s.) Until that time the Church called the writings "the memoires of the Apostles." The earliest reference to the Pauline corpus is from Bishops of the 2nd. cent. Before that time the Church did not refer to any Pauline theology, and none of the Church Fathers commentaries mentions Paul, except in a derogatory way, because Pauline ideas had been adopted by Gnostic churches.
In the beginning there was no central authority and each center of Christian religion had their own Gospel. There were some 20+ Gospels in use during the 2nd. cent. In order to discredit the teachings of some Bishops and to prevent the spread of misinformation (non-orthodox teaching) one of the Bishops argued successfully for only four Gospels to be included in the catholic NT. These were considered to support the Church Doctrine and were attributed to the apostles and called "scripture." The other Gospels were destroyed by the Church, but some copies were preserved in the desert by religious, only to be discovered in 1948, and now translated into English. They have been compiled into the "Ante-Nicene New Testament."
The other books followed and were considered to be also divinely inspired but not yet scripture. The Book of Revelation did not appear in any Bible before the 6th. cent. though it is thought to have been written very early on. In the earliest Bibles there are books that are excluded from our current Bible such as "The Shepherd, of Hermas," and the "Gospel of Thomas." This last contains many hundreds of the sayings of Jesus, and may have been one of the earliest Gospels - unfortunately it contains gnostic ideas and was dropped from the Bible. Though some scholars piously believe that the Gospels were written in the 1st. cent. There have been no NT manuscripts discovered from this period.
The educated opinion of Orthodox scholars is that the Gospels were begun in the last part of the 1st. cent. (but have never been found,) or in the first half of the 2nd. cent. as we have discovered manuscripts with familiar phrases from the Bishops of the 2nd. cent., in their own commentaries.
Upvote:6
The confusing part of this question is that there was no "New Testament" until after everything had been written. And so yes, by the time that the canonical list of New Testament books was compiled (a process that took about 400 years, although the individual books were composed within the first 70) was considered Scripture. Because they were considered Scripture, they were included.
It should be understood that the four Gospels, while only four of many, were the most popular four. Iraneus, in Against the Heresies is insistent that there needed to be four:
the Gospels could not possibly be either more or less in number than they are. Since there are four zones of the world in which we live, and four principal winds, while the Church is spread over all the earth, and the pillar and foundation of the Church is the gospel, and the Spirit of life, it fittingly has four pillars, everywhere breathing out incorruption and revivifying men. From this it is clear that the Word, the artificer of all things, being manifested to men gave us the gospel, fourfold in form but held together by one Spirit.
That said, there were many to choose from. The four we have - Matthew, Mark, Luke, and John, were widely considered the best. Many others (Barnabas, Peter, Judas, Thomas) were either just collected sayings or heretical Gnosticism. Beyond that, others, like Marcion, tried to make their own from scratch. Despite this, these four kept being the most popular, the most profitable, the best for reproof, doctrine, etc...
Bruce Metzger argues that the symbolism may be more of an "after-the-fact" thing, however, saying:
"Among minor [canonical] criteria that the ancients sometimes applied was what may be called 'number-symbolism', of which we have conspicuous examples in Irenaeus and the Muratorian Canon....It is no doubt true that this use of numbers was more often a symbolical interpretation of the facts after the settlement of the different parts of the canon than as a means of determining that settlement." (The Canon Of The New Testament [New York: Oxford University Press, 1997], n. 5 on p. 254)
Over and over again, when seeking to portray an accurate account of how Christians should think and live, however, the stories of these four Gospels kept coming back to the fore as the most important.