John 12:31
“Now is the judgment of this world, now shall the prince of this world be cast down.”
What connection has this with, “I have glorified, and will glorify”? Much, and closely harmonizing. For when God says, “I will glorify,” He shows the manner of the glorifying. What is it? That one should be cast down. But what is, “the judgment of this world”? It is as though He said, “there shall be a tribunal and a retribution.” How and in what way? “He slew the first man, having found him guilty of sin, (for 'by sin death entered') but in Me this he found not. Why then did he spring upon Me and give Me over to death? Why did he put into the mind of Judas to destroy Me?” (Tell me not that it was God's dispensation, for this belongs not to the devil, but His wisdom; for the present let the disposition of that evil one be enquired into.) “How then is the world judged in Me?” It shall be said, as if a court of justice were sitting, to Satan, “Well, you have slain all men, because you found them guilty of sin. But why did you slay Christ? Is it not clear that you did it wrongfully?” Therefore in Him the whole world shall be avenged. But, that this may be still more clear, I will make it plain by an exam ple. Suppose there is some cruel tyrant, bringing ten thousand evils on all those who fall into his hands. If such a one engaging with a king, or a king's son, slay him unjustly, his death will have power to get revenge for the others also. Suppose there is one who demands payment of his debtors, that he beats them and casts them into prison; then from the same recklessness that he leads to the same dungeon one who owes him nothing: such a man shall suffer punishment for what he has done to the others. For that one shall destroy him.
3. So also it is in the case of the Son; for of those things which the devil has done against us, of these shall the penalty be required by means of what he has dared against Christ. And to show that He implies this, hear what He says; “Now shall the prince of this world be cast down,” “by My Death.”
Source: Homilies on the Gospel of John (New Advent)