Zechariah, when Gabriel appears to him as he is burning incense to the Lord in the temple, is “startled and overcome with fear.” (Luke 1:12) Mary, when Gabriel appears to her and speaks of God’s favor, is “deeply troubled by [his] statement, wondering what kind of greeting this could be.” (Luke 1:29)
When Gabriel tells Zechariah that his barren wife Elizabeth is to bear a son and that they shall call him John, Zechariah responds, “How can I know this? For I am an old man, and my wife is well along in years.” (Luke 1:18) Zechariah asks for proof, given his circumstances.
When Gabriel tells Mary that she will be with child and bear the “Son of the Most High” (Luke 1:32) Mary asks, “How can this be?” asking to understand the message, given her circumstances. Gabriel explains, “Nothing will be impossible with God.” (Luke 1:34, 37) With the angel’s explanation which Mary readily accepts, she responds, “I am the Lord’s slave. May it be done to me according to your word.” (Luke 1:38)
Elizabeth later proclaims, “She [that is, Mary] who has believed is blessed because what was spoken to her by the Lord will be fulfilled.” (Luke 1:45)
On the other hand, Gabriel proclaims to Zechariah, “I am Gabriel, who stands in the presence of God, and I was sent to speak to you and tell you this good news. Now listen! You will become silent and unable to speak until the day these things take place, because you did not believe my words, which will be fulfilled at the proper time.” (Luke 1:19-20)
Mary immediately acts, visiting Elizabeth so that the unborn children – Jesus and John – may meet even before their births. John leaps in the womb at the presence of His Lord, the One he will go before to prepare the way for the salvation of God’s people.