When you lift up the Son of Man, then you will realize that I am

Book of Numbers 21:4-9. 

From Mount Hor the children of Israel set out on the Red Sea road, to by-pass the land of Edom. But with their patience worn out by the journey, 

the people complained against God and Moses, "Why have you brought us up from Egypt to die in this desert, where there is no food or water? We are disgusted with this wretched food!" 

In punishment the LORD sent among the people saraph serpents, which bit the people so that many of them died. 

Then the people came to Moses and said, "We have sinned in complaining against the LORD and you. Pray the LORD to take the serpents from us." So Moses prayed for the people, 

and the LORD said to Moses, "Make a saraph and mount it on a pole, and if anyone who has been bitten looks at it, he will recover." 

Moses accordingly made a bronze serpent and mounted it on a pole, and whenever anyone who had been bitten by a serpent looked at the bronze serpent, he lived. 

Psalms 102(101):2-3.16-18.19-21. 

LORD, hear my prayer; 

let my cry come to you. 

Do not hide your face from me 

now that I am in distress. 

Turn your ear to me; 

when I call, answer me quickly. 

The nations shall revere your name, O LORD, 

and all the kings of the earth your glory, 

when the LORD has rebuilt Zion 

and appeared in his glory; 

when he has regarded the prayer of the destitute, 

and not despised their prayer. 

Let this be written for the generation to come, 

and let his future creatures praise the LORD: 

"The LORD looked down from his holy height, 

from heaven he beheld the earth, 

to hear the groaning of the prisoners, 

to release those doomed to die." 

Holy Gospel of Jesus Christ according to Saint John 8:21-30. 

Jesus said to the Pharisees: "I am going away and you will look for me, but you will die in your sin. Where I am going you cannot come."

So the Jews said, "He is not going to kill himself, is he, because he said, 'Where I am going you cannot come'?"

He said to them, "You belong to what is below, I belong to what is above. You belong to this world, but I do not belong to this world. 

That is why I told you that you will die in your sins. For if you do not believe that I AM, you will die in your sins."

So they said to him, "Who are you?" Jesus said to them, "What I told you from the beginning.

I have much to say about you in condemnation. But the one who sent me is true, and what I heard from him I tell the world." 

They did not realize that he was speaking to them of the Father. 

So Jesus said (to them), "When you lift up the Son of Man, then you will realize that I AM, and that I do nothing on my own, but I say only what the Father taught me. 

The one who sent me is with me. He has not left me alone, because I always do what is pleasing to him." 

Because he spoke this way, many came to believe in him. 

“ When you lift up the Son of Man, then you will realize that I am ”

He endured death yet hanged death on the cross and mortal men are delivered from death. The Lord calls to mind a great matter which was figuratively done with the Israelites of old. He says: "As Moses lifted up the serpent in the wilderness, so must the Son of man be lifted up; that every one who believes in him may not perish but have everlasting life" (Jn 3:14). A great mystery is here, as those who read it know... Now Moses was ordered by the Lord to make a brazen serpent and to raise it on a pole in the wilderness and admonish the people, Israel, that, when any of them had been bitten by a serpent, they should look upon that serpent raised up on the pole. This was done: some were bitten, looked, and were healed (Nm 21:6-9). 

What are the biting serpents? Sins, from the mortality of the flesh. What is the serpent lifted up? The Lord's death on the cross. For as death came by the serpent so it was imaged by the likeness of a serpent. The serpent's bite was deadly, the Lord's death is life-giving. A serpent is gazed on that the serpent may have no power. What is this? A death is gazed on, that death may have no power. But whose death? The death of life: if it may be said so, the death of life; yes indeed, for it may be said, but said wonderfully. But should it not be spoken, seeing it was a thing to be done? Shall I hesitate to utter that which the Lord has deigned to do for me? Is not Christ life? And yet Christ hung on the cross. Is not Christ life? And yet Christ was dead. But in Christ's death, death died...; the fullness of life swallowed up death; death was absorbed in the body of Christ. So also shall we say at the resurrection, when triumphant at last we shall sing, "Where, O death, is thy victory? Where, O death, is thy sting?" (1 Cor 15:55).