For People Who Think There Was No Historical Jesus

[Confused Ape]

-and even then "knowing" isn't quite the word. Look at how our resident apologists like to quote this and that?

Knowing as in being able to read the texts. Gospel Dating is a bit haphazard.

Estimates for the dates when the canonical gospel accounts were written vary significantly; and the evidence for any of the dates is scanty. Because the earliest surviving complete copies of the gospels date to the 4th century and because only fragments and quotations exist before that, scholars use higher criticism to propose likely ranges of dates for the original gospel autographs. Scholars variously assess the majority (though not the consensus [29]) view as follows:
Mark: c. 68–73,[30] c. 65–70[31]
Matthew: c. 70–100.[30] c. 80–85.[31]
Luke: c. 80–100, with most arguing for somewhere around 85,[30] c. 80–85[31]
John: c. 90–100,[31] c. 90–110,[32] The majority view is that it was written in stages, so there was no one date of composition.

If copies of first century gospel texts were found in a cave somewhere it could turn out that there are some significant differences.