Throughout the Gospel tradition, Jesus referred to Himself as the Son of Man; 81 times, to be precise. When Jesus healed and forgave the paralytic of his sins, the Pharisees accused him of “blasphemy” for usurping a role reserved for “God alone” (Mark 2:7). Jesus responded by saying that He, “the Son of Man, has authority on earth to forgive sins” (Mark 2:10). He tells his disciples that the Son of Man must be rejected by the leaders of Jerusalem, “killed, and after three days rise again” (8:31). Of all his Christological titles, Jesus preferred “the Son of Man”.
So what did He mean when He invoked this title? A tempting way to answer the question is to say that Jesus was emphasizing His humanity. Indeed, scripture does use the phrase, Son of Man, as an idiom to designate a human person. In the Book of the Prophet Ezekiel, which employs the phrase more than any other book in the Bible, the angels use it to address the prophet Ezekiel: “And he said to me, ‘Son of man, stand on your feet, and I will speak with you.’” (Ezekiel 2:1)
While scripture sometimes uses the phrase as an idiom for man, it becomes difficult to maintain that this was Jesus’ intended meaning. A good example comes from Holy Thursday after the Temple guards arrest Jesus and put Him on trial before the council. There Caiaphas asks Jesus if He is the Messiah, and Jesus responds: “I am; and you will see the Son of Man seated at the right hand of Power, and coming with the clouds of heaven” (Mark 14:62). Caiaphas, the high priest, then rips his garments and accuses Jesus of blaspheming against God. In doing so he rallies the council to sentence Him to death.
A question then arises. Why would Jesus, by identifying Himself as the Son of Man, incur the charge of blasphemy? After all, to blaspheme involves speaking ill of God. A helpful clue to solving this problem comes from the Old Testament. In the passage from Mark 14 cited above, Jesus draws from the imagery of the Book of Daniel:
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 kingdom, that all peoples, nations, and languages should serve him; his dominion is an everlasting dominion which shall not pass away. (Daniel 7:13-14)
Both at His trial and during his Holy Week discourses (Mark 13:26), Jesus identifies Himself with this mysterious heavenly figure who rides upon the clouds. One way to understand why the Pharisees were angry at Jesus’ words is that they believed Daniel’s Son of Man was Divine. As Benedict XVI once remarked, in Mark 14, “[Jesus] seemed to be putting himself on an equal footing with the living God himself.” In fact, the cloud imagery that accompanies the Son of Man also represents the presence of God throughout the Old Testament. Exodus 40:34-35, 1 Kings 8:10-11, Jeremiah 4:13, Psalm 97:2, Joel 2:2 are just a few examples. Ironically, the title Son of Man implies that Jesus is more than a man; he is Divine.
Of course, much more could be said about this topic. An important lesson to take away here is how deeply Jesus' words are rooted in the Old Testament. When Jesus says something that sounds mysterious to us, its seemingly hidden meaning often lies within the words of the Jewish scriptures.
Br. Matthew Heynen, O.P. | Meet the Brothers in Formation HERE
 Joseph Ratzinger, Jesus of Nazareth, 1.303.