Luke is very upfront about his purpose in writing Luke (and Acts). He also informs us that “many” have undertaken to write an account of what happened. He likely had Mark in front of him as he wrote but we cannot know how many “many” signifies. We can take this as evidence that he is a careful historian.
In the account of the angel’s appearance to Zechariah and subsequently to Mary we see quite a difference in attitude. Zechariah the priest, chosen to burn incense before God, rejects the angel’s message as impossible and is left mute until it takes place. He should have known better than to question an angel of God, especially in that place. Mary, on the other hand, is young and innocent and objects knowing that she is a virgin. Mary accepts the brief explanation and responds that she is God’s servant and will accept whatever God sends her way. Jesus came and by age twelve it was obvious that he was not an ordinary kid. He spent three days in the temple courts talking with the scholars and amazing the people with his understanding. In 3:23ff we have his genealogy. What is the significance of Luke providing this information there rather than at the beginning of his account like Matthew?