One of the most common criticisms of the Book of Mormon is that its themes are anachronistic. In other words, it sounds too much like the New Testament to have been written hundreds of years before the coming of Christ. The image of Christ as a "vine" is an example. It is first seen in the Bible in the New Testament when Christ says, I am the true vine, and my Father is the husbandman (John 15:1). How could Nephi have used this image before Christ did? How could this theme be known to him at that time?
Nephi was a prophet who had just seen an incredible vision of the history of the world including the life and ministry of the Savior. He had the spirit of prophecy and taught Messianic principles that would be contained also in the Old Testament if so many plain and precious parts had not been taken away from that record.
When the Dead Sea Scrolls were examined, both the Jews and the non-Mormon Christians were astonished because the scrolls contained so much "New Testament" doctrine but were written prior to the coming of Christ. This finding doesn't surprise a student of the Book of Mormon. It confirms that the Lord was teaching his Old Testament era prophets the higher law long before it was given by the Savior in the flesh.