Galatians is another undisputed letter of Paul written in the mid-50s. Why is this important? Because Paul discusses his interaction with Peter and James, two of Jesus’ primary disciples

Paul makes no claim that any of these “apostles” ever knew a historical Jesus. An apostle is a messenger who has been commissioned to represent the one who sent him. Paul refers to himself as an apostle, but one who has been commissioned by God, not Jesus. Paul insisted that his authority to speak his gospel message came from God’s direct communication with him – not from anyone else. Paul also uses the term apostle to refer to Peter, James, and John, which suggests that they too had been commissioned by God and had a “vision”. What’s important here is that Paul never uses the term “disciple” when referring to an apostle. They were simply “those who were already apostles before me” (Gal. 1:17). This means that the idea of an apostle, as understood by Paul writing in the 50s, was understood in missionary terms and had nothing to do with the idea of disciple! The merger of the idea of a disciple, one who was with Jesus, and the idea of an apostle, one who has had a vision of the risen Lord, would not be combined until the gospels. That is to say, only in the later gospels do we find the claim that Peter and James were disciples of Jesus who literally walked alongside him.

James, in particular is head of the Jerusalem Church. In a tantalizing passage, in Galatians 1:19, Paul writes that “but I did not see any other apostle except James the Lord’s brother.” This would appear to state unequivocally that James was Jesus’ sibling (even though he uses the term Lord and not Jesus). However, this is problematic. Paul uses the word “brother” (Greek adelphos) elsewhere and was a common designation that Christians gave each other. Consider Philippians 1.14 and 1 Cor. 15:5-6:

“14 …and most of the brothers and sisters, having been made confident in the Lord by my imprisonment, dare to speak the word with greater boldness and without fear.”

“5 …and that he appeared to Cephas, then to the twelve. 6 Then he appeared to more than five hundred brothers and sisters at one time, most of whom are still alive, though some have died. Then he appeared to James, then to all the apostles.”

Note that James and Peter are listed separately from “the twelve.”

We also have this passage from 1 Corinthians 9.5:

“Do we not have the right to be accompanied by a believing wife, as do the other apostles and the brothers of the Lord and Cephas?”

Since Paul calls James a “brother of the Lord” in Galatians, it seems reasonable to conclude that James’ church in Jerusalem called themselves “brothers of the Lord.” Thus, I would submit that in this passage the “brothers of the Lord” refers specifically to James’ church. If that is the case, then Paul is not acknowledging any blood relationship between James an a historical Jesus.