Add to this, that of the 14 NT books attributed to the Apostle Paul, only 7 are considered by the majority of mainstream scholarship as authentic Pauline texts . So that means, we only have one author we can verify as being authentically who they say they are out of the 27 books in the New Testament.
To further elaborate on the Pauline epistles/letters.
There is also that school of thought held by many Christians and some scholars that Paul was not a true Apostle. There are arguments concerning the Apostles of Christ denying him. However, that is not my point.
The point is, the aforementioned scholarship hearkens back to Jesus warning to his Disciples prior to his returning to the Father.
Matthew 24.
23 At that time, if anyone says to you, ‘Look, here is the Christ!’ or ‘There He is,’ do not believe it. 24 For false Christs and false prophets will appear and perform great signs and wonders that would deceive even the elect, if that were possible.…
Paul actually exampled everything Jesus warned to beware and dismiss as of his anointing.
“Then if anyone says to you, ‘Look, here is the Christ!’ or ‘Look, there he is!’ do not believe it. For false christs and false prophets will arise and perform signs and wonders, to lead astray, if possible, the elect. But be on guard; I have told you all things beforehand.”
Mark 13:21–23
Paul's epistle Romans 15:18I will not presume to speak of anything except what Christ has accomplished through me in leading the Gentiles to obedience by word and deed, 19
by the power of signs and wonders, and by the power of the Spirit of God. So from Jerusalem all the way around to Illyricum, I have fully proclaimed the gospel of Christ. 20 In this way, I have aspired to preach the gospel where Christ was not known, so that I would not be building on someone else’s foundation.
This is not as widely disputed by scholars as the legitimacy of Paul.However recollecting Jesus warning against believing those who claimed to have seen Jesus or met him after he departed back to Heaven, there is the account of the monotheist pagan emperor Constantine. Constantine claimed to have seen a cross shining forth from the sky prior to his bloody battle at the Milvian bridge.
Constantine claimed to see the cross symbol and hear a voice that said, "In this sign thou shalt conquer".
The old testament tells us those who were hung on a tree were cursed. This is in part why Jesus was crucified on a tree, or cross. Because he was meant to be the last sacrifice taking on the curse of the sins of the world upon himself there.
Why would God in two instances, that of appearing as a light to Saul on the Damascus road, and as a light to a pagan emperor, therein contradict the warning he gave his Disciples about appearances of himself after he departed earth?
Whereas the light bringer, Lucifer, who is prince of this world, would have a vested interest in his capacity to abrogate the purpose of Christ after he departed back to the father. And why would a righteous God anoint a pagan monotheist Roman , when Rome's laws crucified his only begotten son, to conquer under the symbol of the curse ? (the cross or tree that Jesus died on).
These are questions no doubt that propel those minor number of scholars in their scholarship that pronounces Paul at the very least was false. And also that Paul at least three times in his own letters pronounced he was delivering his gospel. Not that he was preaching the gospel of Christ.
Therefore the fact that the books of the New Testament, originally written in Greek, were entirely anonymous are but one issue when considering the credibility of certain of its authors. And one minor point. Of all the books in the new testament a man who never heard the living Jesus preach, never met him in flesh, occupies the majority of the NT with his epistles.
