There has been some discussion on the Brothers of the Lord in Galatians 1.19 as of late. McGrath speaks of forced proposals. One of which I have heard recently. It simply is this – that Brothers of the Lord is Paul’s designation for those within his belief system. This is a rather forced explanation because there is no proof of such a split, nor does it hold up under examination. To do so, you have to show this within the Pauline Epistles, and you can’t. I restrict this to the Pauline Epistles because they came first. While I do think that the Gospels provide relevant historical material, they are afterwards, and thus, in some fashion, interpreting Paul. In Paul’s Epistles, Peter is referred to only twice by that name (Galatians 2.7-8). The other times, he is referred to as Cephas. Here is something else to consider. Peter is called an Apostle. Why is this important? Because in two places, Paul acknowledges the apostles and Cephas.
In both of the cases in which Paul mentions the fact that Jesus had brothers (something later making it’s way into the Gospel of Mark), he also mentions Cephas and the Apostles. Some would have us believe that there is a forced separation between Cephas, Apostles, and the Brothers of the Lord. Yet, Paul denies this. He goes to Cephas. He recognizes Cephas as an Apostle, an Apostle with a dual mission to his own. Paul never calls himself a brother of the Lord. That means that Paul recognized himself as someone alongside Cephas as an ambassador, equal with Peter but not James. This is not a separate group, but a designation within the same group, all of which Paul considers his brothers. But, there is someone else different. There is a group of people identified as the brothers of the Lord. In 1 Corinthians, it is a few, but in Galatians, when Paul goes to Jerusalem to assure others of his school, he meets only James, the brother of the Lord.
1 Corinthians 9:5 Do we not have a right to take along a believing wife, even as the rest of the apostles and the brothers of the Lord and Cephas?
1 Corinthians 9:5 μὴ οὐκ ἔχομεν ἐξουσίαν ἀδελφὴν γυναῖκα περιάγειν ὡς καὶ οἱ λοιποὶ ἀπόστολοι καὶ οἱ ἀδελφοὶ τοῦ κυρίου καὶ Κηφᾶς;
Galatians 1:19 But I did not see any other of the apostles except James, the Lord’s brother.
Galatians 1:19 ἕτερον δὲ τῶν ἀποστόλων οὐκ εἶδον εἰ μὴ Ἰάκωβον τὸν ἀδελφὸν τοῦ κυρίου.
Now, let’s expand this to Mark. Mark portrays Jesus has having a family of a mother, brothers and sisters. Given that Mark is being written between 73 and 75 CE, there is the real possibility that some of these people are still alive. Regardless, this is not understood by anyone except mythicists, not even Paul, to be any other group outside his circle or outside Peter’s circle, but they are recognized to be a group connected to Jesus as kin.
Does Paul every use “brother” as something of physical kin? Why, yes, yes he does. Not only this, but Paul is using it in an outsider status. For Paul, his fellow Jews are his brothers.
Romans 9:3 For I could wish that I myself were accursed and separated from Christ for the sake of my brothers, my kin according to the flesh.
Romans 9:3 ηὐχόμην γὰρ ἀνάθεμα εἶναι αὐτὸς ἐγὼ ἀπὸ τοῦ Χριστοῦ ὑπὲρ τῶν ἀδελφῶν μου τῶν συγγενῶν μου κατὰ σάρκα,
One thing it does tell me, however, is that Paul had respect for the name of Cephas, but knew the name of Peter. Perhaps he knew the story of it. I would suspect that he did. But, Cephas is someone who stands out in the crowd. Further, all are apostles, Paul and Peter. But, there is something special about those with a blood connection to Jesus.