In Acts of the Apostles it is seen that there is really no indication that the apostles called James the brother of John or James the son of Alphaeus were bishops of a Jerusalem Church. In fact there are only two references to James the brother of John, once in Acts 1.13 and the other in Acts 12.2.
And he killed James the brother of John with the sword.
It is very important to note that for the entirety of Acts all we know about the apostle James, the brother of John, was that he was killed--that’s all.
Next, the other apostle James listed as the son of Alphaeus is scarcely mentioned. There is only three references to a character called James who maybe assumed to be the apostle James, son of Alphaeus--Acts 1.13, Acts 15.13 and Acts 21.18.
Again, all we know about the assumed apostle James, the son of Alphaeus, is that he was in Jerusalem and met Saul/Paul
Now, look at the activities of the other apostles like John, Matthew, Judas, Andrew, Philip, Thomas, Bartholomew and Simon Zelotes we hardly have any direct references to them preaching the Gospel outside of Jerusalem except the apostle Peter who is mentioned 56 times and only up to chapter 15.
In Acts, it was not the apostles who preached the Gospels to the Gentiles it was Saul/Paul.
Since it was supposedly known and documented in the Epistles and by Paul’s converts since the time of Aretas that it was Paul with Barnabas and others who preached the Gospel to the Gentiles then how could Christian writers say that it was the twelve illiterate disciples who preached the Gospel to every race of men.
Justin’s First Apology XXXIX
For from Jerusalem there went out into the world, men, twelve in number, and these illiterate, of no ability in speaking: but by the power of God they proclaimed to every race of men that they were sent by Christ to teach to all the word of God
There is no indication that Saul/Paul was illiterate in Acts of the Apostles and the so-called Pauline Epistles, however it is implied in the Gospels that the disciples were illiterate.
It is clear that Justin Martyr had not known of Acts of the Apostles, the apostle Paul and the Pauline Epistles.