We don't even have eyewitness accounts in the gospels, nor was Paul aware of some of the gospel stories about Jesus, apparently being later additions.
Ross Clifford, a former barrister, theologian and affirms the case for the resurrection of Jesus. he has a book "Leading Lawyers' Case for the Resurrection" where he devoted a brief chapter on Greenleaf.
He raises a technical question about the ancient documents rule and suggested that hypothetically a court could admit the gospels as ancient documents, but that does not mean that their specific contents are automatically acknowledged as facts (p. 141).
In Cliffords other book:"Clifford John Warwick Montgomery's Legal Apologetic" ....Clifford states:
"The 'Ancient Documents' rule at common law has traditionally related more to the authentication of the document than with the admissibility of its contents. It does not automatically lead to admission of the substance of the document irrespective of its credibility. The question as to whether the authentication of the gospels under the 'Ancient Documents' rule leads to receiving their substance into evidence is contentious. It could be strongly pleaded there is justification for doing so. Yet, it should be noted such pleading would be met by the adverse party's strong rejoinder" (pp. 60-61 & 63).
Greenleaf argues that in several places there are discrepancies between accounts of Matthew and Mark, sufficient to destroy the probability that the latter copied from the former..But when it comes to the striking coincidences between them,( in style, words, and things in other places) he does not like to attribute such to one copying the other.
Yes, indeed, but I doubt if our theist friends read the actual wording. Just a word here and there and jump to a conclusion. The mere presence of the term 'legal document' is enough to get them excited.