At the end of Luke 1, Zacharias finally speaks after close to a year of silence. He prophesies here (being "filled with the Holy Spirit"), and the general theme is about Jesus the Christ
"Blessed is the Lord God of Israel, for He has visited and redeemed His people, and has raised up a horn of salvation for us in the house of His servant David, as He spoke by the mouth of His holy prophets, who have been since the world begun, that we should be saved from our enemies and from the hand of all who hate us, to perform the mercy promised to our fathers and to remember His holy covenant, the oath which He swore to our father Abraham: to grant us that we, being delivered from the hand of our enemies, might serve Him without fear, in holiness and righteousness before Him all the days of our life" (Luke 1:67-75).
God would visit and redeem His people through Christ. Jesus was developing in the womb and would be "raised up" for a unique purpose. A "horn" is a symbol of power, and Jesus would be the power that made salvation possible. He would come from the lineage of David. God has spoken to man from the beginning through prophets (cf. Heb. 1:1,2). Israel had been told by God (through the prophets) that they would be "saved" for a particular reason. God would save Israel in order "to perform the mercy promised to our fathers and to remember His holy covenant." That is, God would fulfill the oath made to Abraham (cf. Gen. 12:1-3; 22:18; Gal. 3:16). The "land" promise and the "nation" promise had already been fulfilled; now it was time to fulfill the "Seed" promise. The nation had been preserved for this purpose! Christ would come that God may be served by man "without fear." This serving, made possible through Christ, would be done "in holiness and righteousness."
The rest of this prophecy is addressed to the infant John:
"And you, child, will be called the prophet of the Highest; for you will go before the face of the Lord to prepare His ways, to give knowledge of salvation to His people by the remission of their sins, through the tender mercy of our God, with which the Dayspring from on high has visited us; to give light to those who sit in darkness and the shadow of death, to guide our feet into the way of peace" (Luke 1:76-79).
John would be "the prophet of the Highest." He would be called this because he would "go before the face of the Lord to prepare His ways" (cf. Matt. 3; Luke 3). There was no prophet previous to John who was greater than him (cf. Matt. 11:11). Israel had a false idea that the salvation the Messiah would bring would be from political evil. John was needed to tell them that it was from sin that God proposed to deliver them (cf. Mark 1:4). "The remission of sins" would be made available through "the tender mercy of our God." How? Through the "Dayspring"; that is, through the rising of the sun or the dawn of a heavenly day. This reminds me of Malachi 4:2 where the prophet declared that "the Sun of Righteousness shall arise." Christ's coming was the dawn of a new day for all mankind! Travelers in the mountains of Judea would often sit and wait patiently for the morning light, lest they should lose their life by a false step taken in darkness. Christ would provide the light and guidance that man needed for true peace (cf. John 1:4,5)!
"So the child grew and became strong in spirit, and was in the deserts till the day of his manifestation to Israel" (Luke 1:80; cf. 2:40,52). The "desert" here simply means a thinly settled region (not necessarily without vegetation). This is all that inspiration has recorded concerning John's birth and early years of life. The next time he is seen it will be "the day of his manifestation to Israel" when he begins publicly preparing the way for the Lord!