1. The promise made
Mt 1:22-23 "Now all this was done, that it might be fulfilled which was spoken of the Lord by the prophet, saying, Behold, a virgin shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us."
2. The promise kept
Is 7:14 "Therefore the Lord himself shall give you a sign;
Behold, a virgin shall conceive, and bear a son,
and shall call his name Immanuel."
LESSON - God has fulfilled EVERY promise made to mankind in the scripture, especially to Israel regarding the Messiah. You and I in the NT are also recipients of God's promises as well.
Rom 10:9, 10, 13 "That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation. For whosoever shall call upon the name of the Lord shall be saved."
Phil 1:6 "Being confident of this very thing, that he which hath begun a good work in you will perform it until the day of Jesus Christ"
From beginning to end, creation to consummation God is faithful towards His people. Towards you!!