The “Eternal Promise of the Christ” is seen in the opening verses of Luke as Gabriel comes to speak both to Zacharias and Mary. The words which Mary hears summarize the centuries of scriptures, prepared by the Spirit of God to testify of the Christ, his love, hope wisdom and service as our holy Prophet, Priest and King.
After four hundred years of silence, Zacharias was chosen to hear the continuation of the eternal promises of the Christ, and its not without some humor, that the priest honored by God through the use of lots to be selected to enter the temple to offer incense at the time of prayer, through his own disbelief after hearing the message from God through Gabriel, to be struck silent for an additional 9+ months, as a sign to prove all which was revealed to him. After breaking the silence of 400 years, God silences Zacharias to extend the silence a bit longer.
The Gospel teaches us of a well-orchestrated series of events, which broke 400 years of silence and gave us some of the clearest and concise teachings on the nature of Christ, the magnificence of his birth, and the fulfillment of prophecies from centuries earlier, all centered around a maiden virgin named Mary. Those words spoke by the Angel not only expressed how God was going to change the world, but comforted the fears of Mary, as he later did Joseph her husband, and offer us a unique and lasting proclamation of what these events meant then and now.