The angel who appeared to Mary identified the Son who was to be born to her:
31 And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS.
32 He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David. [Luke 1:32]
The angel who spoke to the shepherds on the night of Christ’s birth paraphrased Isaiah:
10 And the angel said unto them, Fear not: for, behold, I bring you good tidings of great joy, which shall be to all people.
11 For unto you is born this day in the city of David a Saviour, which is Christ the Lord. [Luke 2:10–11]
The only difference in the Book of Mormon and the King James texts is the capitalization of the words “Mighty and Everlasting.” Since the capitalization further designate the greatness and the Fatherhood of Christ, it is significant.
Just as Nephi delighted “in proving unto my people the truth of the coming of Christ” (2 Nephi 11:4), the Church periodically proclaims to the world the fulfillment of these prophetic words of Isaiah. For example, as part of one of their Christmas messages the First Presidency wrote: “we do know, that our Redeemer lives, and that the prophetic utterance of Isaiah is fulfilled,” and then they quoted part of Isaiah 9:1–7. We also echo another of Nephi’s declarations; “save Christ should come all men must perish” (2 Nephi 11:6). As the Second Coming of Christ looms on the horizon, the words of Isaiah and Christ will be further fulfilled.