Messianic Exegesis: There is a long tradition of reading this verse as a Messianic prophecy warning Ahaz that Yahweh will establish the true king to rule over his people. The Messianic reading hinges on the “virgin” mother and “Immanuel,” which would be considered a description rather than a name. “Immanuel” means “God with us,” an excellent description of the Atoning Messiah dwelling among mortals as a mortal. Lehi (and therefore Nephi) expected Yahweh to become the Atoning Messiah.
While “virgin” applies to Mary, the KJV translators (and therefore Joseph Smith) were applying a Christian reading to the Hebrew almah (meaning, “young woman”). Certainly a “young woman” may very well be a “virgin,” but information about her sexual status is not inherent in the designation “young woman.” The Hebrew word for virgin is bethulah, as we see, for instance, in Genesis 24:16: “And the damsel was very fair to look upon, a virgin [bethulah], neither had any man known her.”
The shift from “young woman” to “virgin” occurred in the Septuagint, the text of the Hebrew Old Testament translated into Greek in Alexandria under the reign of Ptolemy II Philadelphus (282–246 B.C.). Because the New Testament is written in Greek, it is the Septuagint that is the basis for New Testament proof texts, hence Matthew’s proof of the virgin birth by using Isaiah 7:14: “Behold, a virgin shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us” (Matt. 1:23). This term became a staple of Christian interpretation, and the authority of the Septuagint was accepted over and above the Hebrew text, particularly in this issue. Since early Christians interpreted this Isaiah prophecy as Messianic, modern Christians continue that tradition.
Contextual Exegesis: In the context of Isaiah’s prophecy, a dual level of meaning is possible but an exclusively Messianic interpretation is not. The prophecy is given to Ahaz as a sign, but it can hardly be convincing if it will not be fulfilled for seven hundred years. To be persuasive, Ahaz would have to see it fulfilled and concede that Yahweh’s power was manifest in it. Isaiah’s continuation of the prophecy provides more details about the sign. Victor Ludlow sees the prophecy in the light of a dual fulfillment:
Isaiah declares that a virgin will conceive and bear a son who will be called Immanuel. It is important to note that this refers to two births: a particular birth that would occur during Isaiah’s time as well as the well-recognized birth of the Savior several hundred years later. This earlier, less-known birth is an important one. Isaiah essentially affirms that after a child meeting the stated characteristics was born, Ahaz and his people would see the destruction of Syria and Israel before the lad was old enough to know right from wrong. Thus, within eight to ten years, the king could know that the Lord would preserve Judah.