Isaiah actually refers to two historical figures when he prophesizes of the coming of Immanuel. He foresees the turmoil and the challenges of Israel because of their infidelity to God. He is offering hope at a desperate time in history for the deliverance of Israel out of Babylon. This is recorded in Isa 7:14 where a remnant will survive the persecution and a Messiah will come to deliver them as their Lord and King. He says that his name will be Emmanuel.
The first sign is the birth of the son of Ahaz which will become the King Hezekiah which fulfills the prophecy of Nathan and preserves the Davidic line which remains Israel’s hope. But, there is obviously something more being spoken of in His prophecy than just the historical facts of a delivering king of the people out of bondage. There is more than the historical and here the symbolism takes on more importance with the name Immanuel which means God among us. Beyond Hezekiah there is the prophecy of a Messianic King that fulfills the epitome of the Davidic dynasty and the hope if Israel in the man-God Jesus Christ. Isaiah further explains this in Isa 9:6 where we learn that He will be born of a virgin as the Church understands the Ark of the New Covenant and will be the Anointed "Wonderful counselor, mighty God, everlasting Father, Prince of Peace" and surely the Christ. His virtues speak of His authority and teaching but most of all to His obedience to God as the Savior of the world in Isa 49.
In Isa 53:3-5"He was despised and rejected by men, a man of sorrows, and acquainted with grief, and as one from whom men hide their faces he was despised, and we esteemed him not.
Surely he has borne our griefs and carried our sorrows, yet we esteemed him stricken, smitten by God, and afflicted. But he was wounded for our transgressions, he was bruised for our' iniquities; upon him was the chastisement that made us whole, and with his stripes we are healed" Reading this leaves all doubt as to Jesus being the fulfillment of the Prophesies of Isaiah and confirms that Jesus was indeed “God with us”.