Immediately following this new call of the prophet, we have the account of his encounter with Ahaz. Rezin of Syria and Pekah of Israel had entered into a confederacy against Judah, and a great fear possessed the people. The prophet declares to him that the counsel of these kings shall not prevail if he, that is, Ahaz, will be quiet and trust in God. A sign from Jehovah is offered, but he refuses to ask one. This refusal is an act of unbelief, which the prophet rebukes, and then declares that the sign shall be given, namely, that a child shall be born of a virgin.
This sign had an immediate application, but is the beginning in Isaiah's prophesying of a thought which grows as he proceeds, until it is seen to be Messianic in intention. He ends his message to Ahaz by declaring that judgment will fall on Judah, and proceeds to describe the Assyrian invasion, with its terrible results to the people.
the First Week of Advent