Before we get into this subject I would like you to think about this scenario:
You are a king ,your country is being invaded by the strongest empire on earth and you know you have no chance against it.
Then comes a prophet and tell you this: " God has given you a sign and that sign is that a virgin will be born in 800 hundred years and she will have a son"
Put yourself in this king's position and see how ridiculous this will sound like. You are worried about being eliminate and someone tells you about what will happen in 800 years. No way Isaiah is talking about Jesus because the purpose of his visit is to inform Ahaz that Judah will not be eliminated.
Matthew 1:23 ""Behold, a virgin shall conceive and bear a son, and his name shall be called Emmanuel" (which means, God with us). "
ISAIAH 7:11 " 11: "Ask a sign of the LORD your God; let it be deep as Sheol or high as heaven."
12: But Ahaz said, "I will not ask, and I will not put the LORD to the test."
13: And he said, "Hear then, O house of David! Is it too little for you to weary men, that you weary my God also?
14: Therefore the Lord himself will give you a sign. Behold, the virgin shall conceive and bear a son, and shall call his name Imman'u-el."
1) the word "virgin" is translated incorrectly , the proper meaning is “girl” or “maid”
2) No where in the bible Jesus is called Imman'u-el. And it does not mean Jesus or messiah
3) Prophecy is actually fulfilled in ISAIAH 8:3
ISAIAH 8 " 3: And I went to the prophetess, and she conceived and bore a son. Then the LORD said to me, "Call his name Ma'her-shal'al-hash-baz;
4: for before the child knows how to cry `My father' or `My mother,' the wealth of Damascus and the spoil of Sama'ria will be carried away before the king of Assyria."
The sign is fulfilled and the son is found and Assyria did not take Judah down.