Doubt to prophecy. Zechariah was an elderly priest who doubted the angel that told him, that his wife was going to be having a child. He witnessed firsthand God’s power in his life by the blessing of a child bore to his wife. Filled with the Holy Spirit after the birth of his son, Zechariah sings a prophecy about the coming Messiah. His prophecy proclaims that the coming Messiah, comes in power and brings salvation to all people.