The Bible records that Jesus’ brothers did not believe His claims to be God while He was alive.

• The Gospels report that Jesus' brothers were unbelievers prior to the Resurrection.

  • Then He went home, and the crowd gathered again so that they were not even able to eat. When His family heard this, they set out to restrain Him, because they said, "He's out of His mind." (Mark 3:20-21 CSB emphasis added)

  • Then His mother and His brothers came, and standing outside, they sent [word] to Him and called Him. A crowd was sitting around Him and told Him, "Look, Your mother, Your brothers, and Your sisters are outside asking for You." He replied to them, "Who are My mother and My brothers?" And looking about at those who were sitting in a circle around Him, He said, "Here are My mother and My brothers! Whoever does the will of God is My brother and sister and mother." (Mark 3:31-35 CSB emphasis added)

  • The Jewish Festival of Tabernacles was near, so His brothers said to Him, "Leave here and go to Judea so Your disciples can see Your works that You are doing. For no one does anything in secret while he's seeking public recognition. If You do these things, show Yourself to the world." (For not even His brothers believed in Him.) (John 7:2-5 CSB emphasis added)

An early Christian creed reports Jesus appearing to James. 

• 1 Corinthians 15:3-8 is considered an early Christian creed, dated within 2-8 years after the resurrection.1 Verse 7 specifically identifies James as one of the people Jesus appeared to.

  • Then He appeared to James, then to all the apostles. (1 Corinthians 15:7 CSB)

The Apostle Paul identifies James as a leader in the church.

• In Paul’s letter to the Galatian church, he references a trip to Jerusalem where he met with James and specifically identifies him as Jesus’ brother.

  • But I didn't see any of the other apostles except James, the Lord's brother.(Galatians 1:19 CSB emphasis added)

Non-Biblical sources record James suffering and martyrdom, including:

• Josephus, 1st century Jewish historian, records James’ death by stoning (Antiquities. 20:200).

  • “Having such a character ["rash and daring" in the context], Ananus thought that with Festus dead and Albinus still on the way, he would have the proper opportunity. Convening the judges of the Sanhedrin, he brought before them the brother of Jesus who was called the Christ, whose name was James, and certain others. He accused them of having transgressed the law and delivered them up to be stoned.”2

• Two other sources –  Hegesippus and Clement of Alexandria – mention James martyrdom. We do not have copies of their documents, but they were quoted by Eusebius.3