What does Luke 1:19 mean?
Only two angels are explicitly named in the Bible. One is Michael (Daniel 12:1; Jude 1:9; Revelation 12:7), the other is Gabriel (Daniel 8:16; 9:21). It will be this same angel, Gabriel, who also tells Mary the news that she will give birth to the Son of God (Luke 1:26). Gabriel is speaking to Zechariah (Luke 1:5–7), a priest offering incense (Luke 1:8–10). His message was a promise that Zechariah and his wife, Elizabeth, would finally have a child, and the child would be a powerful prophet of God (Luke 1:11–17).Zechariah's instinct was to doubt this prediction. His question is not about "how" such a birth could occur. It is hesitation to believe it "could" occur. In response, the angel identifies himself and his role in passing along messages from God. This reply is almost indignant. Zechariah would have immediately recognized the name Gabriel, thanks to the angel's appearance in the story of the prophet Daniel. Gabriel's reply is something like a modern English speaker saying, "are you really doubting Gabriel, the one God sends to deliver His messages?"
In a rebuke for his lack of faith, Zechariah will be temporarily unable to speak (Luke 1:20), and apparently unable to hear, as well (Luke 1:62).