It really is unknowable. I've heard arguments from both sides and it's still not something we can be absolutely sure about.
"knowable" and "absolute" are not words that fit well when discussing history.Barring the invention of time travel,the best explanation to historical data,at the present,are varying degrees of plausibility.
I'll just add this. There is a long tradition of the "perpetual virginity" of Mary. So was James the result of god impregnation Mary also?
I'm not a traditionalist,but I have heard arguments in favor of James being from a previous marriage of Joseph.There was no word in Koine Greek for step-brother.
What it says in the New Testament (Matthew) is:Joseph wouldn't know her
until she bore Jesus.
I'll let the Catholics (and others alike) defend Mary's perpetual virginity.My interests are with the historical aspects.
Furthermore, isn't it quite pathetic that the best evidence that Jesus was actually a living breathing human being that actually existed so weak as to come down to this one line? He used "the" instead of "a"...
Who says it's "the best evidence"? Not I.
Dig long enough and hard enough and you'll find that it's not just one piece of evidence that places Jesus within history.It's the most logical explanation to the type of (internal evidence) and amount of (historical references) evidence that we do have.
When added together,the case of historicity becomes likely.Not "knowable",and certainly not "absolute",but again,history doesn't work that way.
The gospels depict jesus as a fairly famous and well known man. They speak of large crowds and miraculous events. None of them are recorded elsewhere and they are the kinds of things people who were writing back then would have written about. But nothing survives.
To the extent jesus was a living man, he was nothing like what the gospels describe.
Jesus preached to the poor,downtrodden,and illiterate of backwater Judea in the 1st century.Educated writers would have been scarce and papyrus expensive.
What we wind up with is oral transmissions of his life.(what could be considered as the Q gospel,though certain scholars disagree.But that's a discussion for another time and place).
It's not until the gospel writers and Paul that we see some form of textual notoriety for the life of Jesus.
The gospel writers would have,I think,attained their information from diasporic Jews returning home from Passover.Relaying second-hand tales of a traveling preacher/healer.Hence the variations in the gospels.
Paul brought the Roman world to attention with the inclusion of gentiles(uncircumcised).
Without these occurrences,Christianity may have not have risen to what would come.
It's a wondrous tale(though not without controversy).The story of a pious Jew who healed the sick,fed the hungry,and preached against the corruption of his day.Falsely accused of sedition.Scourged,ridiculed,and crucified for his practices.All the while,forgiving his executioners for their actions.
His tale was of such profound influence that it set a chain of events into motion that we see reflected in society still today.
If the story ended there it would be no less fascinating.But it was just beginning.