Truly, truly, I say to you, you will see heaven opened, and the angels of God ascending and descending on the Son of Man. JOHN 1:51
Why is Jesus called the Son of Man in verse 51 and elsewhere in the Gospels? It has everything to do with Advent.
It’s not simply because he is human. It’s because the figure of a “son of man” in Daniel 7:13 is both human and far more than human. This was Jesus’s favorite designation for himself—Son of Man. It’s used over eighty times in the Gospels, and only Jesus uses it to refer to himself.
He got the title “Son of Man” from Daniel 7:13–14:
“I saw in the night visions, and behold, with the clouds of heaven there came one like a son of man, and he came to the Ancient of Days and was presented before him. And to him was given dominion and glory and a kingdom, that all peoples, nations, and languages should serve him;his dominion is an everlasting dominion, which shall not pass away, and his kingdom one that shall not be destroyed.”
This is the language of kingship and glory and sovereignty (John 3:13; 5:27; 6:62). But it has a different ring than the titles Son of God and King of Israel. It sounds more lowly and ordinary. So when he used it, his claims to kingship and glory and sovereignty didn’t sound so overt. Only those who had ears to hear broke through to the exalted meaning of the term Son of Man when Jesus used it.
So this time it was not the Jewish leaders who used the title to bring him to the cross. Jesus himself used it that way. The key verse is John 3:14–15: “As Moses lifted up the serpent in the wilderness, so must the Son of Man be lifted up, that whoever believes in him may have eternal life.”
So you could say that the greatest glory Nathanael, or you and I, would ever see is the glory of the Son of Man, the Lord of heaven, whose dominion is an everlasting dominion, lifted up on a cross to die for sinners.
So when you see him this Advent season as Son of God and as King of Israel and as Son of Man, make sure that you see him dying to give you eternal life and, therefore, see him as glorious.
Taken from The Dawning of Indestructible Joy – Daily Readings for Advent by John Piper