Why is it said that the Gospel of Luke presents Jesus as "the Son of Man"?

"According to the Synoptic Gospels, Jesus referred to himself as "Son of man" in three contexts, each with its own circle of fairly distinct meanings. He used this self-designation of

(1) his earthly work and its (frequently) humble condition (e.g., Mark 2:10, 28 parr.; Matt 11:19=Luke 7:34; Matt 8:20=Luke 9:58);

(2) his coming suffering, death, and resurrection (Mark 9:9,12; Mark 14:21 and, above all, Mark 8:31; 9:31; 10:33-34 parr.);

(3) his future coming in heavenly glory to act with sovereign power at a final judgement (e.g., Mark 8:38; 13:26-27 parr.; Matt 24:27=Luke 17:24; Matt 25:31-32; see John 5:27).

These classifications show how the "Son of man" served as a way of indicating Jesus' importance and even universal relevance. This was especially true of the class (3) sayings. In other words, "Son of man" was used to say what Jesus did rather than what he was. It was not and did not become a title in the normal sense — at least not on the lips of Jesus himself". (taken from http://en.wikipedia.org/wiki/Son_of_man_(Christianity)).

Also remember that this term appears 107 times in the Hebrew Bible.

I strongly believe that according to the Word of God that Jesus Christ was called himself the son of man because we were all became sin by a men who was Adam, therefore for us to be saved we needed a perfect men not in the bloodline of adam because this blood was corrupted by sin, that why the birth of Jesus came trough the holy spirit, that was the first time for God to have a son via the holy spirit for this reason Jesus was called the begotten son of God, and then the difference between Adam and Jesus was that adam was tempted as result he sined but Jesus was tempted in everything without commited any sin, and by his obedience he saved us, therefore he is the way, the truth and life that lead us to God and is the one who will come to accomplish God judgement on the earth, so Jesus is not God but the son of God and He is a men. Romans5:12-21, Hebrews4:15.

The Bible says that Jesus became man, and that He remained being God.
John 1:14 "And the Word became flesh"
Colossians 2:9 "For in Him all the fullness of Deity dwells in bodily form".

So He is 100% human and 100% God. One person with two natures, and one of them, Son of Man.

This does not mean that he has a sinful human nature. Because His father is God and not man after all. John 8:42 "Jesus said to them, 'If God were your Father, you would love me, for I came from God and I am here. I came not of my own accord, but he sent me.' "

The answer really doesn't depend on any esoteric interpretation, at all. The term "son of man" is vague only if we forget the Semitic tongue of the authors, where they were saying "son of Adam." The genealogy of Yehoshua (Jesus) in Matthew is meant to show the answer to the promise given to Abraham, so it goes only that far. The genealogy of Yehoshua in Luke, however, is meant to show the answer to the promise given to Adam and Eve in Genesis 3:15, where a seed is promised who will crush the enemy's head.

Who is the son of Adam that fulfills this promise given to Adam? That's Yehoshua. He's not just a son of Adam; he's the son. We now know that we needn't look for another as a fulfillment of the promise. "It is finished."

It also somewhat references a description of the Messiah in Daniel 7, where is mentions:

12 As concerning the rest of the beasts, they had their dominion taken away: yet their lives were prolonged for a season and time.

13 I saw in the night visions, and, behold, one like the Son of man came with the clouds of heaven, and came to the Ancient of days, and they brought him near before him.

14 And there was given him dominion, and glory, and a kingdom, that all people, nations, and languages, should serve him: his dominion is an everlasting dominion, which shall not pass away, and his kingdom that which shall not be destroyed.

First, I would have to argue that all the gospels present Yeshua as a man, because I believe he is a man. But one thing that I find particularly relevant about Luke's gospel is his account of Yeshua after his resurrection.

"And as they thus spake, Jesus himself stood in the midst of them, and saith unto them, Peace be unto you.

But they were terrified and affrighted, and supposed that they had seen a spirit.

And he said unto them, Why are ye troubled? and why do thoughts arise in your hearts?

Behold my hands and my feet, that it is I myself: handle me, and see; for a spirit hath not flesh and bones, as ye see me have.

And when he had thus spoken, he shewed them his hands and his feet.

And while they yet believed not for joy, and wondered, he said unto them, Have ye here any meat?

And they gave him a piece of a broiled fish, and of an honeycomb.

And he took it, and did eat before them." Luke 24:36-43

This shows us that the resurrected Messiah was a human, rather than some spiritual entity floating around like a particle of light.

As far as conservative Christianity goes, the earliest I can find is from John Nelson Darby, the man who made up the "pre-tribulation rapture". The article says:

In the Gospel of Luke, the Lord Jesus is specially brought before us as the Son of man. It has been often remarked the contrast there is between John's Gospel and Matthew's...

...In Luke's Gospel there is what might at first appear a difficulty to the mind, but it brings out Christ in a special way, so I speak of it here. In Luke there is more suffering in Gethsemane than in any other Gospel; and on the cross none at all. Why is this? Because, as man, He is above all that He is passing through. The character of the Lord's sufferings in Luke would lead us to remember, for the precious comfort of our souls, that He was perfect Man - sinless, of course, but a Man. When risen, He says, "Behold my hands and my feet that it is I myself; handle me and see, for a spirit hath not flesh and bones as ye see me have." (24:39) He would bring home to the soul all the blessed truth of how thoroughly He was Man. Look how that is marked in Gethsemane: "When he was at the place, he said unto them, Pray that ye enter not into temptation." (22:40) In Luke you find Him constantly praying as man - perfect man, obedient and dependent. "Man shall not live by bread alone, but by every word that proceedeth out of the mouth of God." (Matt 4:4) In Luke we find Him "all night in prayer to God." (6:12) At another time "He went up into a mountain to pray, and as he prayed the fashion of his countenance was altered," and He was transfigured. (9:28) In Gethsemane, "He kneeled down and prayed, saying, Father, if thou be willing, remove this cup from me; nevertheless, not my will but thine be done. And there appeared an angel unto him from heaven strengthening him, and being in an agony he prayed more earnestly." There you get the Man again.

Also, a man named Ray Stedman has an article called Luke: The Perfect Man. His basis for this is:

"The Son of man is come to seek and to save that which is lost" Luke 19:10

John Darby is a very famous theologian, so as far as I can tell, the phrase "the Gospel of Luke presents Jesus as the Son of Man" originated with him.