Summary: The Advent series this year explores the instances when the Master spoke of the purpose in His coming. This is the first message in this Advent series as Jesus spoke of the purpose of His coming.
“‘Now is my soul troubled. And what shall I say? “Father, save me from this hour?” But for this purpose I have come to this hour. Father, glorify your name.’ Then a voice came from heaven: ‘I have glorified it, and I will glorify it again.’ The crowd that stood there and heard it said that it had thundered. Others said, ‘An angel has spoken to him.’ Jesus answered, ‘This voice has come for your sake, not mine. Now is the judgment of this world; now will the ruler of this world be cast out. And I, when I am lifted up from the earth, will draw all people to myself.’ He said this to show by what kind of death he was going to die. So, the crowd answered him, ‘We have heard from the Law that the Christ remains forever. How can you say that the Son of Man must be lifted up? Who is this Son of Man?’ So, Jesus said to them, ‘The light is among you for a little while longer. Walk while you have the light, lest darkness overtake you. The one who walks in the darkness does not know where he is going. While you have the light, believe in the light, that you may become sons of light.’” 
Drawing near to the cross and the crucifixion which He would suffer on that cross, Jesus repeatedly referred to His passion. The Father Himself verified Jesus’ origin and the purpose for His coming. Those who heard both the Son and the Father were ignorant of what they were hearing, though they knew they had heard something significant.
A VOICE FROM HEAVEN — “A voice came from heaven: ‘I have glorified [My Name], and I will glorify it again.’ The crowd that stood there and heard it said that it had thundered. Others said, ‘An angel has spoken to him’” [JOHN 12:28-29]. So often, we hear or see something, and we cannot process what we heard or saw. It is difficult to grasp that which is beyond our normal experience. Those about Jesus at this time could not comprehend what they heard. John says that it was a voice from heaven, but most said, “It thundered.”
Others, perhaps feeling somewhat more spiritual, thought that an angel had spoken. But, having never heard an angel speak when I knew that it was the voice of an angel, I would be ill-equipped to identify a voice as belonging to an angel. Frankly, I question whether those who thought that an angel had spoken on that occasion would have known what an angel’s voice sounded like. We are left with the implication that it was the voice of God speaking.
There had been other occasions when a voice came from Heaven to command those listening to pay attention to what they witnessed. When Jesus was baptised by His cousin, John the Baptist, those who witnessed that event heard a voice from Heaven. This is Matthew’s account of what happened. “Jesus came from Galilee to the Jordan to John, to be baptized by him. John would have prevented him, saying, ‘I need to be baptized by you, and do you come to me?’ But Jesus answered him, ‘Let it be so now, for thus it is fitting for us to fulfill all righteousness.’ Then he consented. And when Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him; and behold, a voice from heaven said, ‘This is my beloved Son, with whom I am well pleased’” [MATTHEW 3:13-17]. Mark records the same event [MARK 1:9-11], as does Luke [LUKE 3:21-22].
On another occasion, Jesus, accompanied by three disciples, was praying on a mountain. These three disciples heard the voice of the Father. This is the account as recorded by Matthew. “After six days Jesus took with him Peter and James, and John his brother, and led them up a high mountain by themselves. And he was transfigured before them, and his face shone like the sun, and his clothes became white as light. And behold, there appeared to them Moses and Elijah, talking with him. And Peter said to Jesus, ‘Lord, it is good that we are here. If you wish, I will make three tents here, one for you and one for Moses and one for Elijah.’ He was still speaking when, behold, a bright cloud overshadowed them, and a voice from the cloud said, ‘This is my beloved Son, with whom I am well pleased; listen to him.’ When the disciples heard this, they fell on their faces and were terrified. But Jesus came and touched them, saying, ‘Rise, and have no fear.’ And when they lifted up their eyes, they saw no one but Jesus only” [MATTHEW 17:1-8].