The Son of God
And the angel answered and said to her, “The Holy Spirit will come upon you, and the power of the Highest will overshadow you; therefore, also, that Holy One who is to be born will be called the Son of God.”
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The angel Gabriel surprised and troubled Mary with his unusual greeting (verse 29), but it seems she soon grasped that she was being given a message from God, similar to the messages given to Hagar, Sarah and Samson’s mother (Genesis 16:7-14; 18:1-15; Judges 13:3-23). Though each of these women was told she would have a son, the message to Mary was on a completely different level. She would not have the son by a man, but would bear the Son of God!
For more about the announcement to Mary that she would be the mother of the Messiah, see “The Birth of Jesus” and “Miracles of Jesus.”