The priest Zechariah was burning incense in the temple as part of Israel’s worship of God when an angel appeared to him. The angel gave him good news that his prayers for a child would be answered. However, Zechariah expressed doubt when he said: “How shall I know this?” Another translation renders it: “How can I be sure?” He used his age and that of his wife for an excuse. To this, the angel said:
“I am Gabriel. I stand in the presence of God, and I was sent to speak to you and to bring you this good news. Luke 1:19 English Standard Version (ESV)
Because he disbelieved his words, Gabriel announced that Zechariah would be unable to speak until the child, John, was born.
What was the significance of the angel Gabriel’s remarks? For this, let us consult John Calvin:
I am Gabriel …By these words the angel intimates that it was not his veracity, but that of God who sent him, and whose message he brought, that had been questioned; and so he charges Zacharias with having offered an insult to God…
…’Gabriel’ means the strength, or power, or pre-eminence of God, and this name is given to the angel on our account, to instruct us that we must not ascribe to angels anything of their own, for whatever excellence they possess is from God.
The Greek participle, παρεστηκὼς, (standing,) is in the past tense, but everybody knows that the past tense of such verbs is often taken for the present, and particularly when a continued act is expressed. The word εὐαγγελίσασθαι (to convey glad tidings) aggravates the crime of Zacharias; for he was ungrateful to God, who kindly promised a joyful and desirable event.
Therefore, I tell you, whatever you ask in prayer, believe that you have received it, and it will be yours. Mark 11:24 (ESV)