When were the Books of the New Testament Written?
30 A.D. : Jesus is Crucified, Dies and is Resurrected
35 A.D. : Gospel of Matthew
40 to 41 A.D. : Book of James
42 A.D. : Gospel of Mark
42 A.D. : Gospel of John
50 A.D. : Book of 1Thessalonians
51 A.D. : Book of 2Thessalonians
53 A.D. (Spring) : Book of Galatians
56 A.D. (Late Winter) : Book of 1Corinthians
57 A.D. (Late Summer) : Book of 2Corinthians
57 A.D. (Winter) : Book of Romans
59 A.D. : Gospel of Luke
64 to 65 A.D. :Book of 1Peter
65 to 66 A.D. : Book of 2Peter
66 to 67 A.D . : Book of Jude
67 A.D. : Book of 2Timothy
THESE DATES ARE TOO FAR BETWEEN
Yet the Apostles Gospels are pretty much similar. So why are their dates so far between? Because these are the surviving copies. All Christian scriptures (Canon/Gnostic) were written by the Apostles in the same time-frame. The birth of Christianity conflicted with the Roman worship and as Christians went underground many copies were made to ensure that it would survive the persecution.
Christianity was illegal under Roman law. Christians were persecuted and their manuscripts confiscated this how the Empire later was able to compile the New Testament. And at first when Christianity was legalised the many Roman councils removed Gnostic text that conflicted with Roman Worship, decades later however, the Empire abandoned their pagan faith and accepted Jesus (Christianity) but the lost Books were never put back.
This validates that Gnostic literature's must be accepted in order to complete the faith called Christianity. Everything about the Christian faith is based on what Jesus said, everything, because Jesus is the cornerstone of that faith!
And another note: This is also why there are many copies found of the same text of the dead sea scrolls and codex. Many copies were made, some survived better then others explaining the multiple copies. The Dialogue of the Savior is single surviving copy. Written for Jesus as he spoke to his Apostles. What a treat!