James, the Lord's Brother
Concise Bible Dictionary:
Though the word ἀδελφός is used in the LXX in a wider sense than “brother,” it has been judged that its use in the New Testament is restricted to those born of the same mother; and therefore the Lord’s brother could not have been the same person as the son of Alphaeus. Nor is it probable that he was one of the twelve apostles, for we read that “neither did his brethren believe in him” (John 7:55For neither did his brethren believe in him. (John 7:5)). The first mention of the Lord’s brethren being with the apostles is in Acts 1:1414These all continued with one accord in prayer and supplication, with the women, and Mary the mother of Jesus, and with his brethren. (Acts 1:14), and there they are referred to as distinct from them. James the Lord’s brother was seen at Jerusalem by Paul (Gal. 1:1919But other of the apostles saw I none, save James the Lord's brother. (Galatians 1:19)). The being thus designated distinguishes him from the apostle who is simply called James in Galatians 2:9, 129And when James, Cephas, and John, who seemed to be pillars, perceived the grace that was given unto me, they gave to me and Barnabas the right hands of fellowship; that we should go unto the heathen, and they unto the circumcision. (Galatians 2:9)
12For before that certain came from James, he did eat with the Gentiles: but when they were come, he withdrew and separated himself, fearing them which were of the circumcision. (Galatians 2:12). Learned authorities state that in Galatians 1:1919But other of the apostles saw I none, save James the Lord's brother. (Galatians 1:19) the construction of the passage in the Greek does not necessarily imply that James the Lord’s brother was an apostle. He is mentioned also in Matthew 13:5555Is not this the carpenter's son? is not his mother called Mary? and his brethren, James, and Joses, and Simon, and Judas? (Matthew 13:55) and Mark 6:33Is not this the carpenter, the son of Mary, the brother of James, and Joses, and of Juda, and Simon? and are not his sisters here with us? And they were offended at him. (Mark 6:3).