According to Richardson, Richardson and Bentley, some critics have charged that the Book of Mormon use of the Greek words "Alpha and Omega" (3 Nephi 9:18) is an anachronism. However, this is one of several supposed problems in the Book of Mormon that has actually become another evidence.
Of course the English words found in the copies of the Book of Mormon were not engraved as English on the plates. The ancient engravings were translated into English. Yet, the English language is actually a combination of several languages and thus contains words from Latin, German, French, and, significantly, Greek. For example, many English words, such as "critical," music," and "poetry" may be thought to be purely English words, but were actually borrowed from the Greek language. So when the word "critical" is used in Alma 51:9 and 57:16, it must be remembered that this Greek word was not originally engraved upon the plates, but was employed by the English translator (Joseph Smith). Likewise, Alpha and Omega has become an accepted English expression, though it was once purely Greek. To use a literal English translation by saying, "I am the A and the O," or the more ancient "I am the A and the T" would be meaningless to english-speaking readers.
Furthermore, Hugh Nibley notes that in the ancient ritual alphabet of the Mandaeans, a Semitic alphabet, "the first and last letters, the "alpha and omega," are the same and represent "perfection of light and life." Both letters, as E.S. Drower explained, "have as their sign a circle, possibly representing the sun-disk as a symbol of light." Hence, as Nibley contemplated, there may be more behind 3 Nephi 9:18 than a mere literary convention: "I am the light and the life . . . I am Alma and Omega." (Nibley, Since Cumorah, pp. 165-166) [Allen H. Richardson, David E. Richardson and Anthony E. Bentley, 1000 Evidences for the Church of Jesus Christ of Latter-day Saints: Part Two-A Voice from the Dust: 500 Evidences in Support of the Book of Mormon, p. 274]