In a few days, we’ll be celebrating the miraculous birth of Jesus. Have you ever considered how the fact that it happened at all was a miracle? Allow me to explain how God physically preserved and sustained His promise:
Cain & Abel: In Genesis 3:15, God promises that the seed of the woman would crush the serpent’s head. In the very next chapter, unrighteous Cain murders righteous Abel . Could this be the end of God’s promise, over so quickly? Short answer: no.
Abraham & Isaac: God makes childless Abram some gargantuan promises . Abram (later Abraham) has to wait decades until the child of promise, Isaac, is born. Isaac and his wife also struggle to have children. Ishmael, on the other hand, has no difficulty procreating . This whole business of Abraham’s descendants being a great nation seems implausible.
Jacob: In his 12 sons, we begin to see some hope. But a famine threatens to wipe the family out . However, God had acted some 20 years earlier in sending Joseph to Egypt and they are saved from famine. The messianic line is safe.
Exodus: Safe until a murderous pharaoh decides some Jewish population control was needed . To keep His plan on track, God used some women: the Hebrew midwives , Moses’ mother , Miriam, and Pharaoh’s daughter .
80 years later, Moses led the people of Israel out of Egypt and 40 years after that Joshua led them into the promised land. And thus some of the promises made to Abraham were fulfilled .
David: Some centuries later, God chose a ruddy shepherd boy and had him anointed king. The then-king tried to kill him (or have him killed) on a number of occasions . But David outlived Saul.
God revealed to David that He would establish the kingdom of one of David’s sons forever . In the rest of the account of David’s life, we read of the deaths of his sons Amnon, Absalom and Adonijah. God’s promise isn’t looking very healthy at this point.
Athaliah: She was Ahab’s daughter and Omri’s granddaughter , and she married one of David’s descendants. At one point, she went on a killing spree, murdering her own sons and grandsons . Yet again, God used a woman to spare the life of a baby boy . The Davidic line, which had come so close to being snuffed out, was safe.
Babylonian conquest: Not all is well just yet. When the Babylonians conquered Judah, they carried off Jehoiachin, the last rightful heir to the throne . His uncle Zedekiah was then installed as a puppet king. The last hing Zedekiah saw before being blinded by the Babylonians was his sons being killed . So much for the promise of an everlasting Davidic kingdom, it would seem.
Exile: Haman the Agagite devises a plan to kill all Jews in general, and Mordecai in particular . Haman should have listened to his wife . God preserved His people from extermination, and kept the Seed safe.
Jesus’ life: Centuries later, at just the right time , God made good on His promise to send a Messiah. Mary’s pregnancy, we assume, was healthy and uneventful. The baby Jesus was preserved from both childhood maladies and the murderous raging of paranoid king Herod. The Seed was preserved right until the hour for which He came . Then the seed died and produced many seeds —the fulfillment of the promise made to Abraham!
Revelation 12: This chapter can be understood as a ‘behind the scenes of Christmas’. The dragon first tries to devour the child; when that is unsuccessful he pursues the woman; failing at that he turns on the rest of her offspring . God preserved the seed of the woman.
Don’t skip over the genealogies in Matthew and Luke. Read that mix of familiar and unusual names and let yourself be overwhelmed by the God who keeps His promises for redemption even through the most unpromising of times and people!
 1 John 3:12
 Genesis 12:2-3, 15:1
 Genesis 25:12-18
 Genesis 42:1-2
 Exodus 1:16
 Exodus 1:17
 Exodus 2:1-3
 Exodus 2:4-10
 Genesis 15:13-14, 18-20
 1 Samuel 18:10-11, 17, 19:15, etc.
 2 Samuel 7:11-16
 2 Kings 8:26
 2 Kings 11:1
 2 Kings 11:2-3
 2 Kings 24:8-14
 2 Kings 25:7
 Esther 3:6
 Esther 6:13
 Galatians 4:4
 Luke 4:28-30; John 8:58-59
 John 12:24
 FWIW, I don’t think the woman is Mary, but the personification of God’s covenant people.