James was skeptical of His brother Jesus and did not believe. But James transformed from an early critic of his older brother to one of his greatest disciples. Why? Because the skeptic James believed he saw his brother alive from the dead.
His brothers therefore said to Him, “Depart from here and go into Judea, that Your disciples also may see the works that You are doing. For no one does anything in secret while he himself seeks to be known openly. If You do these things, show Yourself to the world.” For even His brothers did not believe in Him. (John 7:3-5)
After that He was seen by James, then by all the apostles. (1 Corinthians 15:7)
Then after three years I went up to Jerusalem to see Peter, and remained with him fifteen days. But I saw none of the other apostles except James, the Lord’s brother. (Galatians 1:18-19)