Bishop Eusebius of Caesarea wrote sometime in the early 2C AD, citing Papias on the composition of the Gospel of Mark:
This also the presbyter said: Mark, having become the interpreter of Peter, wrote down accurately, though not indeed in order, whatsoever he remembered of the things done or said by Christ. For he neither heard the Lord nor followed him, but afterward, as I said, he followed Peter, who adapted his teaching to the needs of his hearers, but with no intention of giving a connected account of the Lord’s discourses, so that Mark committed no error while he thus wrote some things as he remembered them. For he was careful of one thing, not to omit any of the things which he had heard, and not to state any of them falsely.
This is a remarkable passage which reads almost like modern historiography. It does not say that Mark is true because it is inspired Scripture, it says that Mark is true because it is based on eye witness testimony that was recorded more or less faithfully but with some artistic latitude.
So when did the Gospels come to be regarded as true because they were inspired Scripture?
When they were canonized by the Magisterium.
These gospels, and others, were circulating among many early Christian communities. They were not yet canonized as Gospels, and not yet separated out from other gospels.
Eusebius is valuable but is not an eyewitness. He never met Mark, never saw whether Mark ever met Peter, or whether Peter ever met Jesus. I am sure none of the rejected gospels began saying “we base this on second hand information”. Many Scriptures - later rejected by the Magisterium - also claimed direct, eyewitness testimony and/or authorship by apostles.
No, some visible human authority had to announce publicly that Mark was inspired, and the Gospel of Mary not inspired. They (the Magisterium) may have chosen to rely more on Eusebius than on whoever the gnostic equivalent of Eusebius was, or other competing traditions.
No ancient scholar, or for that matter no modern scholar, can really prove Eusebius was obviously better than some other compiler, or that his list was more “authentic”. If he is deemed a credible source today, it is because the Magisterium deemed him credible, and not so much other ancients.
But to answer When ?
While it can be argued Mark, for instance, was inspired in the Mind of God before Time began, or that it was inspired in the personal observations and oral history of Peter, or later when Mark wrote it…For us, it was not regarded as Gospel until the Magisterium declared it to be such. Otherwise it still would be just a gospel, not a Gospel. In fact, without the Magisterium, the Gospel of Thomas, and many others, might today be considered “Gospels”, by consensus or whatever; if the Magisterium had not existed.
First, thank you for the Papias quote, that’s really awesome and I like your assessment of it.
Second, the question in the title is very different from the question at the end of your post. They were inspired at the moment of composition. They came to be regarded as Scripture either at that moment or at a later time. Jimmy Akin cites evidence that the Gospel writers regarded their writings as new Scriptures:
The earliest explicit reference to the inspiration of the Gospels that I could find in William A Jurgens’ The Faith of the Early Fathers, Volume 1 — on page 76 — is from St Theophilus of Antioch, written about the year 181:
Moreover, in regard to the righteousness which the law enjoined, the Prophets and the Gospels are found to be consistent with each other, because they all spoke as being inspired by the one Spirit of God. (St Theophilus of Antioch, To Autolycus, 3, 12)
About one year before that, St. Irenaeus appears to refer to the Gospels as Scripture: We have learned from none others the plan of our salvation, than from those through whom the Gospel has come down to us, which they did at one time proclaim in public, and, at a later period, by the will of God, handed down to us in the Scriptures, to be the ground and pillar of our faith. For it is unlawful to assert that they preached before they possessed perfect knowledge, as some do even venture to say, boasting themselves as improvers of the apostles. For, after our Lord rose from the dead, [the apostles] were invested with power from on high when the Holy Spirit came down [upon them], were filled from all [His gifts], and had perfect knowledge: they departed to the ends of the earth, preaching the glad tidings of the good things [sent] from God to us, and proclaiming the peace of heaven to men, who indeed do all equally and individually possess the Gospel of God. Matthew also issued a written Gospel among the Hebrews in their own dialect, while Peter and Paul were preaching at Rome, and laying the foundations of the Church. After their departure, Mark, the disciple and interpreter of Peter, did also hand down to us in writing what had been preached by Peter. Luke also, the companion of Paul, recorded in a book the Gospel preached by him. Afterwards, John, the disciple of the Lord, who also had leaned upon His breast, did himself publish a Gospel during his residence at Ephesus in Asia. source The things to notice here are that St. Irenaeus names the authors of all four gospels and gives their writings as examples of what the Apostles “handed down to us in the Scriptures.” Thus he identifies the Gospels as Scripture.
The texts were of course divinely inspired when they were written. Many of the books were widely used and were recognized as inspired/authoritative prior to any council. However, there was dispute over some books throughout their history, and certainly even though some books were widely accepted there wasn’t a definitive statement binding all the faithful to accept it (though for a layperson or presbyters obedience to the bishop was expected). It was definitively declared by the Church at various councils such that there could be no more doubt about the books they declared on.
Of course, to be recognized as inspired is not the same as to be recognized as “New Testament”. The early Christians had lots of books recognized as inspiring, as did the Jews, which are not in the Old or New Testaments. Obviously the early readers of Mathew could not say “this book is in, or will someday be in, the New Testament”, because they had no such concept.
Their Jewish contemporaries did not have something called the Old Testament. They had writings of very different importance, some of which Christians now lump together as the OT, others which we might not recognize. Some Christians, a portion of who were Jewish, regarded the Hebrew Scriptures as the **only **inspired texts that were scripture. Other Christians considered (many more than 27) Christian, more-or-less- inspiring texts as the only Scripture - no OT as scripture.
Some visible human authority must have decided that there should be something called “Old Testament”; a term had to be invented; that it will still be considered scripture, and that a selection of the inspiring Christian texts would also be considered Scripture: some authority invented a term, “New Testament”. Then certain inspiring books were left out - like the Didache, which is not heretical, and considered inspiring by many Christians for 2000 years. Also excluded were many other books.
So even while early Christians were certainly blessed, inspired, and guided by Luke, and Didache, from the earliest times, it was only after the “New Testament” was declared that Luke could be inspiring to readers **as Scripture. **
Only after the action of the Magisterium could Luke be fully separated out, for readers, from Didache, the Gospel of Mary, etc. It became part of a different category.
Your facts are generally correct, but you are confusing “inspired” (by the Holy Spirir) with “inspiring” (to readers). Certainly the inspired Scriptures are inspiring to many, but that is not the criteria for their being inspired.
That Scripture is inspired by God when written, is only in so far as the Catholic Church has declared what writings comprise Sacred Scripture.
The Catholic has no difficulty here, because he accepts the infallible teaching of the Catholic Church that it is indeed Inspired. Further discussion from that point of view would lead to a study of the credentials of the Catholic Church as a divinely guaranteed teacher of religious truth.