Isaiah 7:14 NIV

 Therefore the Lord himself will give you a sign: The virgin will conceive and give birth to a son, and will call him Immanuel.

The Lord had called Isaiah to encourage Ahaz (did not do right) son of Jotham (did do right) while the Northern Kingdom attacked Jerusalem/Judah.  2 Kings 16 says that Ahaz made a deal with Assyria, and even built an altar to impress them, this may have been after this section of Isaiah.  The Lord gave Ahaz the opportunity to ask for a sign that Isaiah’s prophecy would come true.  Ahaz refused and in so doing angered God.  His refusal sounded good, but probably stemmed from Ahaz’s pride rather than true belief in the Lord.  Verse 9b is an awesome verse, and is truth to last the ages.

Verse 14 is the heart of Christmas, and Jesus’ mission in just fifteen words.  Once again, we see the Lord being faithful and offering hope, even though the judgement of Judah/Israel was being predicted.