Doctrinally, this is the pinnacle of this chapter. The Lord gives a wicked king, Ahaz, a kernel of prophetic truth that he most certainly won't understand. The part he understands comes in verse 16, 'the land that thou abhorest shall be forsaken of both her kings.'
Some have misconstrued Mary's immaculate conception by questioning whether or not she was actually a virgin. The scriptures leave no doubt. We also learn that Joseph did not consummate his marriage with Mary until after the birth of Jesus, 'And [he] knew her not till she had brought forth her firstborn son: and he called his name JESUS' (Matt 1:25). All we need to know about how God the Father is the literal and physical Father of Jesus Christ is contained words of the angel to Mary, 'The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God' (Lu 1:35).
The name Immanuel means "God with us." It is given as a title of the Son of God, not as his given name. Isaiah commonly uses titles to describe the Messiah, 'his name shall be called Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace' (Isa 9:6). "Immanuel" is also spoken of in Isaiah 8:8.
Marion G. Romney
"Here is another example in which men revise the scriptures without the inspiration of the Spirit. Isaiah, in predicting the birth of Christ, said: 'Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.' When Isaiah used the word virgin, he was saying that a woman who had not known a man should bear a son.
"The modern translators say: 'Behold, a young woman shall conceive and bear a son, and shall call his name Immanuel.' (Holy Bible, Revised Standard Version of Isa 7:14 [New York: Thomas Nelson and Sons, 1952]) You see, they do not believe that Christ was divine, so it does not make any difference to them whether they say a 'young woman' or a 'virgin.'" (Conference Report, Tokyo Japan Area Conference 1975, p. 46 as taken from the 1981 Old Testament Institute Manual, p. 145)