Luke 1:20

“And behold, you will be silent and not able to speak, until the day that these things will come about, because you did not believe my words, which will be fulfilled in their season.”

Because he had not believed Gabriel’s words, which Gabriel stressed would be fulfilled, Zacharias was to be struck dumb for some time (ese siopon). He was to be silent and not able to speak. In Scripture silence was the prelude to extraordinary events. Compare Revelation 8:1; Lamentations 3:26; Habakkuk 2:20; Zephaniah 1:7; Zechariah 2:13. It was a sign that God was about to work. Thus the very sign indicated the awesomeness of this moment.

The impression given is that he should have believed, for he had as examples of God’s ability to give a child in old age the examples of Sara (Genesis 21:1-2) and Hannah (1 Samuel 1:6; 1 Samuel 1:19), and he had been informed of it by an impeccable source. But instead he had doubted, and he could not be allowed to take his doubt out to the people. So God gave him a sign which would also be a sign to the people. God would use his weakness for good, for his dumbness would make an impression that his doubting words might not have, and his releasing from it will be an indication that a new prophet has been commissioned. It was thus not just a punishment. It was a chastening with a purpose. Compare Ezekiel 3:26-27. In Ezekiel’s case his dumbness was a sign that God had nothing further to say to the people. And his mouth was opened when his ministry could begin again. Thus if they saw Zecharias’ dumbness as indicating that God had at present nothing to say to them it might make the people think more carefully about their position before God in a way that Zacharias’ doubting words might not. His dumbness thus indicated the final days of silence before the new prophet was born.