Let’s read Luke 1:8-18:
Now while he was serving as priest before God when his division was on duty,  according to the custom of the priesthood, he was chosen by lot to enter the temple of the Lord and burn incense.  And the whole multitude of the people were praying outside at the hour of incense.  And there appeared to him an angel of the Lord standing on the right side of the altar of incense.  And Zechariah was troubled when he saw him, and fear fell upon him.  But the angel said to him, “Do not be afraid, Zechariah, for your prayer has been heard, and your wife Elizabeth will bear you a son, and you shall call his name John.  And you will have joy and gladness, and many will rejoice at his birth,  for he will be great before the Lord. And he must not drink wine or strong drink, and he will be filled with the Holy Spirit, even from his mother’s womb.  And he will turn many of the children of Israel to the Lord their God,  and he will go before him in the spirit and power of Elijah, to turn the hearts of the fathers to the children, and the disobedient to the wisdom of the just, to make ready for the Lord a people prepared.”
 And Zechariah said to the angel, “How shall I know this? For I am an old man, and my wife is advanced in years.”
R. Kent Hughes rightly notes that for a priest, “the honor of offering incense was the grandest event in all his earthly existence. Many priests had never had the privilege, and no priest was allowed to offer it more than once.”3 Inside the temple, the priests were offering the sacrifices, outside the worshipers were praying. At one point, Zechariah was to step behind the tall, thick, and beautiful curtain. He was to enter into the Holy of Holies, after which he would purify the altar and would then offer the incense that signified that the sacrifices were heading up to God in that incense of prayer.
The ecstasy of serving the Lord in this manner was soon replaced by another extreme emotion — sheer terror. “And there appeared to him an angel of the Lord standing on the right side of the altar of incense. And Zechariah was troubled when he saw him, and fear fell upon him.” One thing here: remember how Zechariah was one who walked in the commandments of the Lord and was blameless. As a priest, he knew the Scriptures and had read about how the angel of the Lord and appeared to a few select men in the past — and they all reacted the same way: with sheer terror.
The angel however, tells Zechariah that the unthinkable will happen — a son! And notice the name: “you shall call his name John.” The name ‘John’ means “God has been gracious” or that “God has shown favor.” For so long, it seemed as if their prayers had landed on deaf ears or that it just wasn’t part of God plan to bless them with a child. Given their age, they may have just gotten used to not having a child and had grow callous to what others said about them.
This child would not just be any child. We read a lot about his character, but we learn all we need to learn about John from Jesus’ own lips: “I tell you, among those born of women none is greater than John” (Luke 7:28, ESV).
It was not by random chance that Zechariah was chosen by lot. God planned on using them to bring in the forerunner. And when we as followers of Christ realize this truth, we find great freedom in our lives. But here is where Zechariah asks his question of unbelief. “How shall I know this?”
If you don’t believe how deep our unbelief can move, I want to remind you of a story of the rich man and Lazarus. Lazarus was a poor man who believed and loved God with all he had. The rich man did not care — even with Lazarus begging at his gate. They both died, with Lazarus going to heaven, the rich man going to hell. Notice the conversation:
 The poor man died and was carried by the angels to Abraham’s side. The rich man also died and was buried,  and in Hades, being in torment, he lifted up his eyes and saw Abraham far off and Lazarus at his side.  And he called out, ‘Father Abraham, have mercy on me, and send Lazarus to dip the end of his finger in water and cool my tongue, for I am in anguish in this flame.’  But Abraham said, ‘Child, remember that you in your lifetime received your good things, and Lazarus in like manner bad things; but now he is comforted here, and you are in anguish.  And besides all this, between us and you a great chasm has been fixed, in order that those who would pass from here to you may not be able, and none may cross from there to us.’  And he said, ‘Then I beg you, father, to send him to my father’s house—  for I have five brothers —so that he may warn them, lest they also come into this place of torment.’  But Abraham said, ‘They have Moses and the Prophets; let them hear them.’  And he said, ‘No, father Abraham, but if someone goes to them from the dead, they will repent.’  He said to him, ‘If they do not hear Moses and the Prophets, neither will they be convinced if someone should rise from the dead.’ “
Back to our first point: just because you know the doctrines and the stories and the commands of Scriptures does not mean you believe in the biblical sense. And if you fail to hear the Word of God and submit to what God reveals in every area of your lives, even if God himself arrived on the scene, you would not be convinced.
You see, we often sing about how we want the presence of God in our lives — how we want to “see him.” But if we do not listen to the ones whom he has sent