In the birth of Christ, the world finds new birth. In our natural birth, we are alienated from God until we are redeemed through Christ and born anew spiritually. This new birth changes our whole nature: Those who are re-born in Christ are given the status of sons and daughters of God and become co-heirs with Christ (Romans 8:17). This is why, when we pray, we can now address God as "Our Father."
Jesus, the Son of God, in being born to human parents, also became the son of another father. Likewise, while we in our natural birth are sons and daughters of our earthly fathers, when we are spiritually reborn we are born under new parentage and become sons and daughters of God. God in His love wants to make us His children and sent His only Son into the world so that He could create many more sons through Him.
In the Old Testament, having a large family was a sign of blessing from the Lord. This is perhaps most evident in God's promise to bless Abraham by giving him many descendants. This sign of blessing through many offspring foreshadows God's plan to bring many sons and daughters into His own family. It is a blessing to God Himself to have many children.
Christ's birth would mean the birth of many new sons and daughters throughout the centuries. His birth is what makes our birth in Him today possible, and it paved the way for God to have many children. While Christ's physical birth into our world holds very literal and physical significance for us, it is also a sign and a symbol to us of what God is creating in each of our hearts and in His kingdom.
Our God, who is "making all things new" (Rev. 21:5) began by sending His Only Son, the Ancient of Days, to earth as a newborn. Just as Jesus was made new in the form of a baby, we are being made new, and the world will be made new. He was the forerunner of our faith and of our new life. His birth, His baptism, and His death and resurrection all blazed the path for us as new sons and daughters of God.
In the time between Christ's birth and His second coming, His command to all His followers is to make more disciples: God still wants more children and wants to bring many sons to glory (Heb. 2:10). At this time we can celebrate the fact that Christ our Savior, and our Brother, was born to bring about the birth of many more sons and daughters, bringing glory and blessing to God.