What does Mark 3:17 mean?

While Matthew 10:2 and Luke 6:14 list Peter's brother Andrew next, Mark goes straight to James and John. Peter and the sons of Zebedee become Jesus' closest friends. Along with Peter and Andrew, Jesus had already chosen them to be disciples early on (Mark 1:19–20).

The James referred to here is not the same person who wrote the book of James. That letter was written by Jesus' half-brother and the leader of the church in Jerusalem. This James, John's brother, is the first martyr, and his execution by Herod is the only apostle's death mentioned in the Bible, except for that of Judas Iscariot (Acts 12:1–2).

John becomes one of the most influential of Jesus' apostles. He is not to be confused with John the Baptist, or John-Mark, the author of the Gospel of Mark and the cousin of Barnabas (Colossians 4:10). This John is the author of the Gospel of John; the letters 1, 2, and 3 John; and the book of Revelation. His Gospel is unique in that it focuses on the theology of Christ more than the miracles. John is also known as the disciple whom Jesus loves (John 13:23; 19:26; 20:2; 21:7). Although all the disciples love and admire Jesus, no one else is shown to be so assured of Jesus' love except maybe Mary of Bethany.

Despite John's simple devotion, he and his brother can be impulsive. Boanerges is Aramaic for "sons of rage" or "sons of thunder." Jesus' nickname for the brothers reflects that they have the destructive zeal of a thunderstorm. They live up to their name when they ask Jesus for places of honor in His kingdom (Mark 10:35–40). James, John, and Peter are the only people mentioned to whom Jesus gives nicknames.