The other Gospel accounts go right into John’s ministry, never mentioning his parents or the circumstances of his birth. What did Luke want to express to Theophilus by speaking of Zechariah’s experience as a righteous priest?
Luke begins and ends his Gospel narrative in the Temple. This would direct Theophilus’ attention to the priesthood, its duties to their brethren and to its service to God in the Temple ceremonies. Zechariah was a priest belonging to the course of Abijah, the 8th division of the 24 division priesthood (Luke 1:5). This means his time of service came close to the time of Pentecost. Each division served for one week and all divisions served during the Holy Days—like Passover and Pentecost (Feast of Weeks). Every 6 months the courses would begin again.
Theophilus did not believe in angels, so an angel appearing to Zechariah would be meant for him to reconsider his theology. But, is this all? No, I believe Luke’s point goes much deeper than this. Zechariah and his wife, Elizabeth were old, how old the text doesn’t say. I believe the Greek could mean and elderly couple or that Elizabeth was past menopause, meaning in her 50s. Zechariah could be a little older, perhaps 60 or more. The angel began by telling Zechariah that his prayer was answered (Luke 1:13)! Was Zechariah praying for a son? I don’t think so, because he doesn’t believe the angel. The fact is, the angel offered the miracle birth as a sign that Zechariah’s prayer would be answered. Fathering a son was probably the farthest thing from Zechariah’s mind at the time.
So, what was Zechariah praying for? I think we get a hint from Elizabeth’s greeting to Mary. Notice that she mentions how honored she was that Mary, the mother of her Lord, would come to her home (Luke 1:42-43)! Elizabeth was saying she understood Mary was the mother of the Messiah—the Lord of all Israel. Zechariah, apparently, was praying for the coming of the Messiah—many people at this time were looking for the Kingdom of God (Luke 2:25, 38 & Luke 23:42, 51), or the coming of the Messiah, because they knew Daniel’s 70 Weeks Prophecy (Daniel 9:24-27) was coming to a close. Believers knew the Messiah would be born into that generation of the Jews.
Luke was reminding Theophilus through Zechariah’s prayer that the Messiah was supposed to have come at the very time of Jesus birth, and the 70 Weeks Prophecy of Daniel would have been fulfilled in Jesus’ lifetime. Theophilus could not have missed this, and Luke was seeking to cause him to reconsider what he was doing to the followers of Jesus during his tenure as High Priest in 37-41 CE, for Acts tells us that the Jewish persecution of Hellenistic Jewish believers in Jesus continued to the end of the decade.