God's sign that Judah would be delivered from the threat of the armies of Israel and Syria was the birth of a son to a virgin. The son would be called Immanuel, God with us. This was a prefiguring of the birth of God's Son to the Virgin Mary to be the Savior of all mankind.
Our churches teach that the Word, that is, the Son of God [John 1:14], assumed the human nature in the womb of the Blessed Virgin Mary. So there are two natures—the divine and the human—inseparably joined in one person. There is one Christ, true God and true man, who was born of the Virgin Mary, truly suffered, was crucified, died, and was buried. He did this to reconcile the Father to us and to be a sacrifice, not only for original guilt, but also for all actual sins of mankind [John 1:29].
He also descended into hell, and truly rose again on the third day. Afterward, He ascended into heaven to sit at the right hand of the Father. There He forever reigns and has dominion over all creatures. He sanctifies those who believe in Him, by sending the Holy Spirit into their hearts to rule, comfort, and make them alive. He defends them against the devil and the power of sin. (paragraphs 1-5)
APOLOGY OF THE AUGSBURG CONFESSION The adversaries approve Article III, in which we confess that there are two natures in Christ. The human nature was assumed by the Word into the unity of His person [John 1:14]. Christ suffered and died to reconcile the Father to us and was raised again to reign, to justify, and to sanctify believers according to the Apostles' Creed and the Nicene Creed. (paragraph 1)
Condensed from CONCORDIA: THE LUTHERAN CONFESSIONS, copyright 2005,2006 by Concordia Publishing House. Used by permission. All rights reserved. To purchase a copy of CONCORDIA, call 800-325-3040.