The oldest evidence of the New Testament is dated to a fragment which is called Papyrus p52
The front (recto) contains parts of seven lines from the Gospel of John 18:31–33, in Greek, and the back (verso) contains parts of seven lines from verses 37–38.
I Would say even that the original Gospel of John was written between 38-47AD(If one reads carefully what i say he will understand why)
At the very end of the Gospel of John - 21:24 it says:
'This is the disciple who testifies to these things and who wrote them down. We know that his testimony is true.'
The 'We know' are probably some other disciples of Jesus who wrote down what one of the Apostles told them.
Some early manuscripts containing the text of this chapter are: Papyrus 66 (c. AD 200; extant verses 1–9, 12, 17) Papyrus 109 (3rd century; extant verses 18–20, 23–25)
What we have today as evidence is miracle since they did not know how to preserve evidence as they were not looking that far in the future.What preserved all of what we have today as the Bible is the clergy of the Early Church.They preserved a message for 3 centuries.That means between 8-12 generations.The are also other writings in History that just make the events highly probable.
For someone to talk about his childhood would have to know him at that time.We don't have much of a choice since Mary and Joseph would be the reasonable ones.Joseph is out as he died before Jesus' ministry.So that leaves Mary.
Mary went with John in Ephesus between 38AD-47 AD
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So if they left and stayed there , it would be logical that they were written after their departure by people who knew John.
The question is Did anyone else went with John,or it was just Marry? If it were from the Church in Ephesus , then it will be logical to assume that they have keeped this document.But we have no such thing , so that is why the only plausible explenation is that the Gospel would have been writen as late as around 50AD,earlier dates also plausible.
The Apostoles went their own way.
'We know' possibly gives emphasys to the original writer/s.
If the Gospel of John is contributed to John and is his testimony , then anything after 47AD seems absurd.The Gospel of John is unique because of the text in it - it is a testimony of someone.
If this really is the testimony of John the Apostle , then the Gospel of John cannot be written after 50AD(because with time people forget things) as the writers would have trouble to memorize all of that.The narrative in the Gospel is very clear in some parts.It's a testimony.
What is considered today may be all wrong.
Revelation and John have two separate writers.
One is John the Apostle , the other is John the Elder.
It is interesting to note that there was a 'John' listed as being a member of the High Priest’s family (Acts 4:6). Specifically, the text states that Annas, Caiaphas, John, and Alexander all shared in high-priestly descent (Acts 4:6).
Was this John later known as John, the Elder? There is also an ancient letter of Polycrates of Ephesus written to Victor of Rome that described John, the Elder, as 'a priest [who] wore the high-priestly plate on his forehead.' This would explain why John was exiled to Patmos. It was common for the Romans to exile disfavored aristocrats, but others, like Peter and Paul, were simply executed or enslaved.
John is a common 1st century name and the narrative in Revelation is different from that in Revelation.
But i have doubts about Thomas and how he would posses this information.
It is not clear how Thomas met Jesus and when.
After Jesus died Thomas went to India, then to China, and back to India.
The 'Gospel' is found near Nag Hammadi, Egypt.I don't see how that can be Thomas.
The Gospel of Thomas is not included in the Bible because it contains controversial material that Early Orthodox Christian leaders did not agree with, specifically the gnostic theme of knowledge in place of the traditional sacrament of baptism and Holy Communion.
The Gospel of Thomas has some gnostic elements but lacks the full gnostic cosmology.it's orign is dated in the middle of the second century.
The original Gospels are much more reliable source for Jesus Christ's childhood.