One of the features of biblical writing – and particularly of the Gospels – that would be regarded as evidence for factual reporting if it appeared in any other historic document is that the stories often report conversations and actions that might reflect discredit on those the author expects us to admire.
Mark Shea has a brief passage in his latest NCR post talking about the crucifixion – and specifically about Jesus’ quote from Psalm 22:
I understand what you are saying about Psalm 22 and the Todah (“Thanksgiving”) sacrifice and agree with it. However, my point is that, to somebody unfamiliar with Jewish scripture (like yer average ancient pagan), this and other passages from the Gospels are not something that anybody inventing the story would include. If you are an apostolic fraud with a dead rabbi on your hands and you are trying to fake him up as a god for a bunch of suckers, you don’t put words that sound like cries of powerlessness and despair on his lips, just as you don’t have him ask questions or profess ignorance. That looks bad. A fake god does not say, “Of that day and that hour, no one knows, neither the angels in heaven, nor the Son.” Gods are supposed to be omniscient and such statements therefore raised awkward questions. So (if you are a liar writing fiction) you have him say, “I know when the End is, but you are not worthy to be told.” Similarly you don’t record, “My God, my God why have you forsaken me?” You don’t record, “Who touched me?” You don’t record that he was crucified at all, but invent some other way to end the story (such as the Islamic expedient of having Judas get crucified and Jesus whisked away to heaven). Much tidier and more obviously a happy ending. Otherwise, you will find yourself with exactly the problem the apostles had: fellow Jews who say, “Cursed is every one who is hanged upon a tree.”
In short, my point is that the Gospel writers do record these things — because they are not faking up a story but recording what happened and letting the chips fall where they may. They have the first mark of honest witnesses in that they record things which seem at a prima facie level to obviously look bad to their case.