The angel Gabriel struck Zechariah mute, and possibly deaf, some experts say, merely because Zechariah asked how it would be possible for him and his wife to have a child: “I’m an old man, and my wife is up there in years, too” (Luke 1:18). Gabriel got ticked by that. And it could seem as though he overreacted. Why do you think Gabriel struck Zechariah mute? He didn’t do that to Mary when she questioned how she could get pregnant since she was “a virgin” (Luke 1:34).
There’s no indication about why Gabriel treated Zechariah like that. Perhaps we are getting just part of the story reported in this Gospel, and if we knew all the facts, we would understand why Gabriel did what he did. But because he did strike Zechariah unable to speak, the story of the birth of John the Baptist became so dramatic that Luke decided to include it in his book about the life and teachings of Jesus. If the story hadn’t been so dramatic, with Zechariah miraculously recovering the ability to speak at the birth of his son, who knows if there would have been any mention of the birth of John the Baptist.