When it came to his brother’s bold claims, James was a skeptic. James, his brothers, and even his mother thought Jesus had “lost his senses” and showed up once when he was teaching “to take custody” of him (
Mk. 3:21). Another time, Jesus’ brothers told him to go to Judea, where the Jews were seeking to kill him (
Jn. 7:2–4) since “not even his brothers were believing in him” (
Jn. 7:5).
“A prophet is not without honor,” Jesus said, “except in his hometown and among his own relatives and in his own household” (
Mk. 6:4).
They did think He was out of His mind. The Greek word used in Mk 3:21 is:
1839 eksístēmi (from 1537,
ek, "out of," and 2476,
histēmi, "to stand") – literally, "to remove from a standing (fixed) position," put out of place; i.e. "beside oneself," showing someone as flabbergasted (completely stupefied); at a total loss to explain or account for something; overwhelmed, astonished (amazed).
In context, they were not amazed at how wonderful and profound His teaching was but were amazed at how irrational they felt He had become. There is nothing in the Scripture to suggest their concern was the pace of His preaching. John 7:5 tells us that His brothers were not putting their faith and trust in Him. In context, that is clearly a reference to His claim to deity. Having grown up with Him, they knew He was loving, honest, hardworking, etc, so they had no trouble believing those things about Him. They never saw Him sin. What was there not to believe? His claim to deity. That was the bridge too far for them. He was the model brother, but the Son of God?
While there is no Scripture telling us Jesus told His brothers who He was, His ministry was public, and at times, the Pharisees accused Him of blasphemy for claiming to be equal to God. One time, a crowd tried to throw Him off a cliff. Another time, they were going to stone Him. It is highly unlikely they knew nothing of His claim to deity. Word would have gotten around. If they were genuinely astonished (in a good way) by His teaching and only concerned for His physical well-being, we would not be told they did not believe in Him (Jn 7:5). While they never saw Jesus sin, they had never seen Him perform a miracle. Constantly preaching is not a sign of being out of your mind. It is a sign of being devoted to your task. While we know Jesus hungered and got tired, nothing is said about His poor health due to His constant preaching and teaching. What would make them think He was out of His mind was the things He was claiming.