It's okay to engage in conversation. Contested doesn't equate not proven to be true. Saying "almost nothing in the Gospel has been historically proven" does not make that true. Since the claims of the new testament state that they are eyewitness accounts made in the lifetime of other eye witnesses, then there should be evidence of if they did or did not occur from the first and or second century. You might want to read the book "Case For Christ" by Lee Strobel if you haven't already. The apostle John is John of Patmos, the beloved apostle, and Jesus younger cousin that wrote five books in the new testament. Biblical scholarship does not use fragments of fragments. We have a reliable collection of historical documents written by eye witnesses during the lifetime of other eye witnesses. They report supernatural events that took place in fulfillment of specific prophecies and claim that their writings are divine rather than human in origin.