All judgment given to the Son of Man

 J. N. Darby wrote:

All that has been entrusted to man, man has failed in. And God has put all into his hands first, to be set up perfect in the second Man who never fails.

Adam himself fails and is replaced by Christ.

The law was given, and Israel made the golden calf; hereafter, when Christ comes, the law will be written in the heart of Israel.

The priesthood failed, strange fire was offered and Aaron forbidden to enter the sanctuary, save on the great day of atonement, and then not in his garments of glory and beauty; Christ is a merciful and faithful high priest even now in glory.

The son of David set up in person wholly fails, loving many strange women, and the kingdom is divided. Nebuchadnezzar set by God over the Gentiles makes a golden image, puts those faithful to God into the fire, and becomes a beast. Christ shall take the throne of David in unfailing glory, and rise to reign over the Gentiles.

The Church was called to glorify Christ. I, says He, am glorified in them. But antichrists and a falling away are the result: even in the apostle's time all seek their own; and the last days (John), the objects of judgment (Jude), were there. After Paul's decease grievous wolves would come, and from the bosom of the Church those who turned away the disciples would arise, and perilous times and evil men and seducers waxing worse and worse, and if they did not continue in God's goodness, they would be cut off: but He will come, for all that, to be glorified in His saints and admired in all them that believe. The Church has fallen like all the rest. ("The Church - the House and the Body", Collected Writings, Vol. 14, pp. 98–99)

(My memory is that he makes similar summaries elsewhere, but this is the first example I found.)

This, to me, summarizes Darby extremely well. God has delegated authority to man, man has failed, and so God restores His plan in His own second Man (1 Corinthians 15:47). 

This helps us understand Christ's words in John 5:26–27, "the Father... has given [Christ] authority to execute judgment [also], because he is Son of man." That last clause is striking: we might expect Him to say that the Father has given Him authority to execute judgment because He is the Son of God. That would make sense, right? because we know that God is the Judge of all the earth (Genesis 18:25, Romans 2:3). But that's not what He says, He says it is because He is the Son of Man that He has been given authority to execute judgment.

It takes us back all the way to Genesis 1:27–31, where God puts man over all the creation and calls it "very good," and to Genesis 2:15–20, where God brings every creature to Adam "to see what he would call them" (Genesis 2:19). God has put man over creation, and He works within that delegated authority to fix the ruin man has brought in.

Paul repeats this claim in Acts 17:30–31. God has appointed a Man to judge the whole earth, and has made it clear who that Man is, by raising Him from the dead. Again, it's remarkable that Paul emphasizes Christ's manhood in discussing judgment: it is the Son of Man who will judge.

Of course that doesn't mean that God isn't the judge of all the earth. Paul is explicit that God will judge "by the Man whom He has appointed" (Acts 17:31). It's not that this Man will act independently: He will execute God's judgement. He acts, if we can say it this way, as God's representative.

William Kelly points out that Adam was made "in the image and likeness of God," but that has changed in the fall:

In Genesis 5 we have the generations of Adam. Upon this I would not now dwell farther than to draw attention to the commencing words, "In the day that God created man, in the likeness of God made he him; male and female created he them; and blessed them, and called their name Adam in the day when they were created." But "Adam," it is said, "begat a son in his own likeness, after his image." It was no longer in the likeness of God, but in the image of God always. For man, now as ever, fallen or not, is in the image of God; but the likeness of God was lost through sin. ("Genesis," Lectures on the Pentatuech).

Kelly points out elsewhere that Christ "is the 'image of the invisible God.' But He is never called His likeness, for this were to deny His glory" ("The Revelation of God").

We were made in God's image to represent Him in this creation, acting on authority He had delegated to us. We have ruined that. It is Christ who will eventually make this right. We don't see it yet, but we know it is coming (Hebrews 2:5–9).

And notice how 1 Corinthians 15:21–22 builds on this same theme: since by man came death, by man also resurrection of the dead. There is a symmetry that's explicit in the chapter.

I mentioned before that I was in a meeting where someone said that the point of Romans 6 is that we need to embrace our identity in Christ. That skips over a whole lot of the content of Romans 6:1–11, but it is a profound summary. 1 Corinthians 15:22 says something like that: in Adam all die, in Christ shall all be made alive. There are these two identities, and we are to embrace the one and eschew the other. Our dying with Christ – "with Christ," not "in Christ" – has freed us from what we were "in Adam" to be "in Christ." Again, I know there's a lot more to it, but this is a good thumbnail sketch.

It is very easy for us to lose sight of the significance of Christ's manhood. I remember one day realizing that Christ has never stopped being Man: it was a profound turning point in my mind. One man brought in death, another Man has brought in resurrection. One man was given judgment over this earth, another Man will execute that judgment.

I remember someone saying in meeting, "the only accomplishment of man that will last into eternity are the wounds of the crucifixion." That was a touching and sobering thought, but it's not really true. There is a Man who has redeemed us and will present us to God (Isaiah 53:11).  There are accomplishments of that Man that certainly will last through eternity.