I do not often answer questions directly on this site, but since this one fits the theme of the crucifixion which I have been writing about this week, I thought I would post it publicly.
Question: Why did Jesus “give” his mother to John when He was hanging on the cross?
Answer: A very good question. The passage relevant to your question can be found in the book of John.
Now there stood by the cross of Jesus His mother, and His mother’s sister, Mary the wife of Clopas, and Mary Magdalene. When Jesus therefore saw His mother, and the disciple whom He loved standing by, He said to His mother, “Woman, behold your son!”7Then He said to the disciple, “Behold your mother!” And from that hour that disciple took her to his own home. (John 19: 25-27)
Though the Bible does not explicitly state it, the evidence indicates that Joseph, Mary’s husband, had died before this time. The last we hear of Joseph was when Jesus was twelve years old (see Luke 2: 41-50). It seems that Joseph died while Jesus was somewhere between 12 and 33 years old. As the oldest son Jesus would have assumed the responsibility as the head of the household. Knowing that He was going to die, Jesus honored the fifth commandment by making provision for His mother.
The next question to consider is this: why did Jesus not assign the care of His mother to His brothers? Again, the Bible does not explicitly say why Jesus told John to provide for Mary. However, the evidence does point to a logical conclusion.
We do not know how many children Mary and Joseph had after Jesus, but we do know there were several. They were Jesus’ half-siblings because they had Joseph as their father while Jesus was conceived of the Holy Spirit. One of Jesus’ brothers, James, went on to become an important figure in the early church and pastored the church in Jerusalem. He also wrote the book of the Bible that bears his name. So why, then, did Jesus not tell James to take care of their mother?
The answer is found in John 7. In verse 5 we read “For even His brothers did not believe in Him.” The gospels make it clear that Jesus’ siblings did not believe in Him until after the resurrection. We know that Jesus appeared to James, for 1 Corinthians 15:7 says “After that He was seen by James.” It is probable that this event is what finally inspired James to believe in His brother as the Son of God.
At the time Jesus hung on the cross, His siblings did not believe in Him. It stands to reason, then, that He would ask one of His followers to care for His mother. He selected John, his closest friend who is consistently referred to as “the disciple Jesus loved,” to take on this responsibility. We can assume that if James had believed in Jesus at this time, He would have received this responsibility.
NOTE: The Catholic Church teaches that, because of Mary’s perpetual virginity, Jesus had no siblings. I do not know how the Catholic Church answers this question.