The verses in 2 Nephi 12 (Isaiah 2) deal with the ushering in of the millennial era and the changes that will accompany it. The writings of Isaiah as found in the Book of Mormon show the following additional phrase in verse 5: "Yea, come, for ye have all gone astray, every one to his wicked ways" (2 Nephi 12:5). This verse indicates a widespread apostasy in Israel and the return of Israel to the Lord before the Second Coming. Student Manual for Religion 302 Old Testament: 1 Kings-Malachi, p. 139]
For Ye Have All Gone Astray Every One to His Wicked Ways
John Tvedtnes writes that in comparing the Isaiah text from the King James Bible with the Book of Mormon, we find at the end of 2 Nephi 12:5 (compare Isaiah 2:5) a phrase is added. The verse reads: "O house of Jacob, come ye and let us walk in the light of the Lord; yea, come, for ye have all gone astray, every one to his wicked ways." (added phrase in italics) This additional phrase is also found in Isaiah 53:6 and is hence the kind of thing that Isaiah would be expected to say. There is evidence to indicate that the Massoretic Hebrew Text deleted this portion by haplography because of its resemblance to words around it. An earlier Hebrew scribe can therefore be credited with this accidental deletion. [John A. Tvedtnes, "The Isaiah Variants in the Book of Mormon," FARMS, p. 22]