The angel that visited Zacharias declared great things to him about John, the son his wife would bear him. How did the priest reply? "And Zacharias said to the angel, 'How shall I know this? For I am an old man, and my wife is well advanced in years.' And the angel answered and said to him, 'I am Gabriel, who stands in the presence of God, and was sent to speak to you and bring you these glad tidings. But behold, you will be mute and not able to speak until the day these things take place, because you did not believe my words which will be fulfilled in their own time'" (Luke 1:18-20).
The angel's name was Gabriel, meaning "hero; mighty one of God" (cf. Rev. 8:2). Zacharias showed a lack of faith in the promise the angel delivered by asking for proof of the truthfulness of it. He does not believe Gabriel's good news, because he thinks he and his wife are too old to have a child. His moment of doubt here would end up costing him at least 40 weeks of silence (cf. Matt. 12:36,37)! Zacharias was deprived of his speech (and apparently his hearing, according to Luke 1:62). This was an appropriate punishment for not believing the angel's words. It was also a sign, immediately evident to all. With his speech, he had demonstrated unbelief; the punishment became a means of instruction and mercy.
"And the people waited for Zacharias, and marveled that he lingered so long in the temple. But when he came out, he could not speak to them; and they perceived that he had seen a vision in the temple, for he beckoned to them and remained speechless" (Luke 1:21,22). Evidently, the people knew how long it should take for Zacharias to fulfill his duty in the Holy Place. The Jews considered slow service as both irreverent and displeasing to God. They become disturbed when he exceeded their time expectations (cf. Lev. 16:13). When he did come out, he was unable to dismiss them with the usual blessing (cf. Num. 6:23-26). Disbelief is always powerless to bless. They perceived that he had seen a vision probably because of his excited manner.
"So it was, as soon as the days of his service were completed, that he departed to his own house. Now after those days his wife Elizabeth conceived; and she hid herself five months, saying, 'Thus the Lord has dealt with me, in the days when He looked on me, to take away my reproach among people'" (Luke 1:24,25). Zacharias did not allow his recent handicap to hinder him from fulfilling his duties. He went to his home after his days of service were completed. Elizabeth then conceived a child naturally, like Sarah (cf. Gen. 21:2) This conception is unlike the miraculous (i.e., unnatural) conception of Jesus (cf. Luke 1:31-35). The reason why Elizabeth hid herself is unknown. In these early months of her pregnancy it would not be necessary to hide oneself in order to keep the pregnancy a secret. Likely her reasoning had to do with her mingled feelings of modesty, humility, devotion, and joy. Her reproach of being childless was ending (cf. Gen. 30:23). She might have remained secluded longer perhaps if Mary had not come to visit her.