The song asks the honest question, “Mary, did you know?” What did you know, and when did you know it? For some, the lyrics rub the wrong way with the course feeling of mansplaining to Mary, “Hey, did you know your Son wasn’t just some random kid?” The very notion is a non-starter: That Mary was clueless about her Son’s identity and mission.
Mary knew what she heard from the angel Gabriel, “Do not be afraid, for you have found favor with God. And now, you will conceive in your womb and bear a son, and you will name him Jesus. He will be great, and will be called the Son of the Most High, and the Lord God will give to him the throne of his ancestor David. He will reign forever, and of his kingdom there will be no end.” (Luke 1:30-33)
Mary knew what her distant relative Elizabeth had declared, “Blessed are you among women, and blessed is the fruit of your womb. And why has this happened to me, that the mother of my Lord comes to me? For as soon as I heard the sound of your greeting, the child in my womb leaped for joy. And blessed is she who believed that there would be a fulfillment of what was spoken to her by the Lord.” (Luke 1:42-45)

Mary knew what the angel told her husband, “‘Joseph, do not be afraid to take Mary as your wife, for the child conceived in her is from the Holy Spirit. She will bear a son, and you are to name him Jesus, for he will save his people from their sins.’” (Matthew 1:20-21)
Mary knew what shepherds heard from the heavenly host, “Do not be afraid; for see – I am bringing you good news of great joy for all the people: To you is born this day in the city of David a Savior, who is the Messiah, the Lord. You will find a child wrapped in bands of cloth and lying in a manger.” The shepherds said to one another, “Let us go now to Bethlehem and see this thing that has taken place, which the Lord has made known to us.”
So they went with haste and found Mary and Joseph, and the child lying in the manger. When they saw this, they made known what had been told them about this child, and all who heard it were amazed at what the shepherds told them. (Luke 2:10-18)

Mary knew what her elders Simeon and Anna said when Mary and Joseph presented their 8-day-old bundle of joy in the temple, even before the arrival of the Wise Men, even before Joseph’s dream to save Jesus from the murderous King Herod. “Simeon took the baby Jesus in his arms and praised God, saying, ‘Master, now you are dismissing your servant in peace, according to your word; for my eyes have seen your salvation, which you have prepared in the presence of all peoples, a light for revelation to the Gentiles and for glory to your people Israel.’” (Luke 2:28-32)
Mary knew. Twice the Holy Spirit overshadows her, and twice she treasures all that has happened, pondering such remarkable events in her heart. (Luke 2:19, 51). She thinks about everything long and deeply, with rich insight into what God was doing in and through her – little Mary, meek and mild.

Mary knew! Maybe not all the particulars about Jesus’s entire ministry, including his passion, death, and resurrection. She did know, however, via Simeon, that “a sword” one day would pierce her own heart and soul.
Mary probably didn’t have any special foreknowledge of miracles like Jesus walking on water and calming of the storm. But the Old Testament prophet Isaiah would have given Mary a clue about Jesus giving sight to the blind. Isaiah predicts what is yet to come: “The Spirit of the Lord is upon me, because he has anointed me to preach good news to the poor. He has sent me to proclaim release to the captives, and recovery of sight to the blind, to set at liberty those who are oppressed, to proclaim the year of the Lord’s favor.” (Isaiah 61:1-3, Luke 4:18)
Mary thus knew that the sleeping child she was holding would usher in the kingdom of God.
The full humanity and divinity of Christ remains a mystery, and exactly how Mary understood or articulated that mystery is a question that Scripture doesn’t fully answer. Though Mary knew intimately who Jesus was. She carried him for nine months, and she alone knew beyond any possibility of doubt that there was no human father.
Mary’s “yes” to God was a moment of singular grace. Without her “yes,” there’d have been no incarnation – no God coming to us in human form and pitching his tent among us. Mary would not unwillingly become the mother of God, nor would Mary’s “yes” have been so blessedly meaningful had she not understood what she was agreeing to.
When she said “yes,” Mary knew what it meant: God had chosen her for deep, overwhelming privilege. Mary also knew – deep in her heart of hearts, I suspect – that she was consenting to unsupportable sorrow. God did not foist that on her either. When Simeon issued his warning, Mary undoubtedly heard nothing she didn’t already know.
Mary knew. And from the get-go, she knew it all – or at least the parts that mattered most to a broken and fearful world.
Pastor Grant M. VanderVelden shared this message on the Seventh Sunday of Advent, December 22, 2024, at First Presbyterian Church in Waukon, Iowa, USA. Reflection by Steven D. Greydanus informs the message. Illustrations are by Phil Boatright and come from the children’s book Mary Did You Know? The Story of God’s Great Plan by Mark Lowry.