Were the apostles a bunch of illiterates?

A reader writes:

I was in an argument with my brother who is an atheist, who was arguing that none of the writings in the New Testament could have been written by the Apostles, because they were illiterate fishermen. I was wondering if you had any thoughts or knew about any resources concerning this topic of New Testament authorship.

I address notions like that in this piece:

It is worth noting that the *evangelists* are not always the same as apostles. Luke is a doctor, not an illiterate. Matthew is a tax collector (literacy required). Mark is not a fisherman and obviously not illiterate (since he does, after all, write a gospel). And the rumors that John was illiterate merely because snooty members of the Jerusalem elite regarded the apostles with disdain do not make for a persuasive case. Much of the “illiterate fisherman” meme comes from Hollywood, not from the actual text of the NT, nor from the internal witness of the gospels. There is good reason to think that John was actually quite well-educated and came from a fairly well-off family. He was, for instance, “known to the High Priest”. This suggests strongly that his family hobnobbed with the Jerusalem elite. It’s quite possible that John was regarded by the Jerusalem elite as a young well-to-do radical from a good family who had fallen in with a nutty cult.