I agree that the word of God can make big changes in your life. Once you're saved the Holy Spirit convicts you of sin and reminds you of what you've read in the Bible.

I don't think you can say that the word changed James. There wasn't a New Testament then. James would have been familiar with the Old Testament. What changed James was a visit from the risen Christ. As Paul said,

(1 Corinthians 15:3-8 NIV) For what I received I passed on to you as of first importance : that Christ died for our sins according to the Scriptures, {4} that he was buried, that he was raised on the third day according to the Scriptures, {5} and that he appeared to Peter, and then to the Twelve. {6} After that, he appeared to more than five hundred of the brothers at the same time, most of whom are still living, though some have fallen asleep. {7} Then he appeared to James, then to all the apostles, {8} and last of all he appeared to me also, as to one abnormally born.

The book of James is thought to be the first New Testament book that was written. James the Apostle was killed by Herod in 44 AD. James the Lord's brother became just as prominent as Peter and John.