What does Luke 1:41 mean?

Elizabeth is six months pregnant (Luke 1:36), despite being older and formerly barren (Luke 1:5–7, 13). Her child will come to be known as John the Baptist (Luke 3:2–3), an important precursor to the Messiah (Luke 1:14–17). As it happens, that very Messiah is in the womb of a young virgin named Mary (Luke 1:26–27). She was recently informed she was to bear the Son of God, Jesus Christ (Luke 1:31–33). In her excitement, Mary has come to visit Elizabeth's home in the hills near Jerusalem.

The arrival of Mary causes an immediate reaction. Her voice causes the unborn baby in Elizabeth's womb to move in a dramatic way. At the same time, Elizabeth feels herself filled with the Holy Spirit. These responses speak to the miraculous nature of both pregnancies. They also imply something important about the unborn in general. Both Jesus Christ and John the Baptist were identifiable, distinct persons. At this moment, Elizabeth's son is three months from birth and Mary's pregnancy has only just begun. And yet, the two are already alive, active, and individual.

Elizabeth will celebrate this turn of events (Luke 1:42–45), as will Mary (Luke 1:46–47).