Allen & David Richardson and Anthony Bentley note that the Book of Mormon was written by prophets who were conversant with Hebrew customs and language (1 Nephi 1:2). Part of the Hebrew language was a style of writing called “prophetic perfect.” In the prophetic perfect style of writing, the prophet who speaks of the future describes the event as if it had already occurred. For example, “But behold I have obtained a land of promise” (spoken by Lehi while in the wilderness Valley of Lemuel before they left on their journey, 1 Nephi 5:5); “After [Christ] was baptized with water, the Holy Ghost descended upon him in the form of a dove” (spoken by Nephi approximately 550 years before Christ’s birth, 2 Nephi 31:8); “These are they whose sins [Christ] has borne; these are they for whom he has died, to redeem them from their transgressions” (spoken by Abinadi approximately 150 years before Christ’s birth, Mosiah 15:12).
Angela Crowell noted the following in her article entitled “Hebraisms in the Book of Mormon”:
The Prophetic Perfect is a common usage in the language of the prophets. The prophet so transports his mind ahead that he describes a future event as if it had been already seen or heard by him. This happens in making promises or threats, and also in the language of contracts.
[Allen H. Richardson, David E. Richardson, and Anthony E. Bentley, Voice from the Dust-500 Evidences Supporting the Book of Mormon, p. 268]