Read Isaiah 7:10-16
10 The Lord sent another message to Ahaz: 11“Ask the Lord your God to give you a sign. It can be from deep in the world of the dead or from high up in heaven.”
12 Ahaz answered, “I will not ask for a sign. I refuse to put the Lord to the test.”
13 To that Isaiah replied, “Listen, now, descendants of King David. It’s bad enough for you to wear out the patience of people—must you wear out God’s patience too? 14Well then, the Lord himself will give you a sign: a young womank who is pregnant will have a son and will name him ‘Immanuel.’l 15By the time he is old enough to make his own decisions, people will be drinking milk and eating honey.m 16Even before that time comes, the lands of those two kings who terrify you will be deserted.
...the LORD himself will give you a sign: a young woman who is pregnant will have a son and will name him 'Immanuel.' - Verse 14
Jesus birth is God's proposal - God's word - God's sign to us... will we receive the message?
Lord you have sent us your sign, you have shown us the way of righteousness - lead us - teach us to follow you.