First let's read the text. I'm going to italicize a few important lines.
Luke 1:5-8: In the days of Herod, king of Judea, there was a priest named Zechariah... and he had a wife of the daughters of Aaron, and her name was Elizabeth. 6 And they were both righteous before God, walking in all the commandments and ordinances of the Lord blameless. 7 But they had no child, because Elizabeth was barren, and both were advanced in years. 8 Now while he was serving as priest before God when his division was on duty, 9 according to the custom of the priesthood, it fell to him by lot to enter the temple of the Lord and burn incense. 10 And the whole multitude of the people were praying outside at the hour of incense. 11 And there appeared to him an angel of the Lord standing on the right side of the altar of incense. 12 And Zechariah was troubled when he saw him, and fear fell upon him. 13 But the angel said to him, “Do not be afraid, Zechariah, for your prayer is heard, and your wife Elizabeth will bear you a son, and you shall call his name John. 14 And you will have joy and gladness, and many will rejoice at his birth; 15 for he will be great before the Lord, and he shall drink no wine nor strong drink, and he will be filled with the Holy Spirit, even from his mother’s womb. 16 And he will turn many of the sons of Israel to the Lord their God, 17 and he will go before him in the spirit and power of Elijah, to turn the hearts of the fathers to the children, and the disobedient to the wisdom of the just, to make ready for the Lord a people prepared.” 18 And Zechariah said to the angel, “How shall I know this? For I am an old man, and my wife is advanced in years.” 19 And the angel answered him, “I am Gabriel, who stand in the presence of God; and I was sent to speak to you, and to bring you this good news. 20 And behold, you will be silent and unable to speak until the day that these things come to pass, because you did not believe my words, which will be fulfilled in their time.”
Let's sum up what happened here.
1. Gabriel appears to a priest
2. The priest is troubled (1:12)
3. Gabriel says, “Do not be afraid” (1:13)
4. Gabriel announces the birth of a child and gives his name: “you shall call his name John” (1:13)
5. The child is described as having an eschatological role (e.g., like Elijah, cf. Luke 1:16-17; Mal 4:5-6; Sir 48:10).
6. Zechariah asks: “How shall I know this?” (1:18)
7. Zechariah explains that he is unable to have children (1:18).
8. He does not believe and is made mute until John’s birth (1:20).
Now let's look at the Annunciation to Mary:
Luke 1:26-38: In the sixth month the angel Gabriel was sent from God to a city of Galilee named Nazareth, 27 to a virgin betrothed to a man whose name was Joseph, of the house of David; and the virgin’s name was Mary. 28 And he came to her and said, “Hail, full of grace, the Lord is with you!” 29 But she was greatly troubled at the saying, and considered in her mind what sort of greeting this might be. 30 And the angel said to her, “Do not be afraid, Mary, for you have found favor with God. 31 And behold, you will conceive in your womb and bear a son, and you shall call his name Jesus. 32 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 father David, 33 and he will reign over the house of Jacob for ever; and of his kingdom there will be no end.” 34 And Mary said to the angel, “How shall this be, since I have no husband?” 35 And the angel said to her, “The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born will be called holy, the Son of God. 36 And behold, your kinswoman Elizabeth in her old age has also conceived a son; and this is the sixth month with her who was called barren. 37 For with God nothing will be impossible.” 38 And Mary said, “Behold, I am the handmaid of the Lord; let it be to me according to your word.” And the angel departed from her.
Let's sum up what we've read here:
1. Gabriel appears to a virgin
2. Mary is "troubled" (1:29)
3. Gabriel says, “Do not be afraid” (1:30)
4. Gabriel announces the birth of a child and gives his name: "you shall call his name Jesus" (1:31)
5. The child is described as having an eschatological role (he is the Davidic Messiah, cf. Luke 1:32-33).
6. Mary asks: “How can this be…” (1:34)
7. Mary explains that she is unable to have children (1:34).
8. Mary responds in faith (1:38)
There are numerous similarities here. Yet, the similarities underscore the striking difference between Zechariah’s response and Mary’s. Whereas Zechariah, a priest serving in the temple fails to believe, Mary, a poor young peasant woman, responds in faith. If there's ever a place where an ancient Israelite would expect to have an angelic vision it's in the temple! Yet, Mary, whose angelic visitation is almost exactly like Zechariah's, believes the angel's word.
Indeed, she is "full of grace"!