What evidence do you have that the Gospel authors did not have familiarity in Greek as well as Hebrew?
>> “What evidence do you have that the Gospel authors did not have familiarity in Greek as well as Hebrew?” <<
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Get real! - They were poor working class men.
Further, the Hebrew language is YHVH’s language, given specifically for conveying his word to all.
It is not likely that anything in the NT was first written in any other language, except for certain letters by Paul, that may have been written in the native language of the intended recepients. Paul was the only apostle commissioned to the gentile world.