Diverse Things are Spoken Concerning the Same Christ, on Account of the Diverse Natures of the One Hypostasis [Theanthropic Person]. Why It is Said that the Father Will Not Judge, But Has Given Judgment to the Son
30 Lest, however, we may seem to conjecture this rather than to prove it clearly, let us produce a certain and plain sentence of the Lord Himself, by which we may show that this was the cause why He said, “The Father judges no man, but has committed all judgment unto the Son,” viz. because He will appear as Judge in the form of the Son of man, which is not the form of the Father, but of the Son; nor yet that form of the Son in which He is equal to the Father, but that in which He is less than the Father; in order that, in the judgment, He may be visible both to the good and to the bad.
For a little while after He says, “Verily, verily, I say unto you, He that hears my word, and believes in Him that sent me, has everlasting life, and shall not come into condemnation; but shall pass from death unto life.” Now this life eternal is that sight which does not belong to the bad. Then follows, “Verily, verily, I say unto you, The hour is coming, and now is, when the dead shall hear the voice of the Son of God, and they that hear shall live.” And this is proper to the godly, who so hear of His incarnation, as to believe that He is the Son of God, that is, who so receive Him, as made for their sakes less than the Father, in the form of a servant, that they believe Him equal to the Father, in the form of God.
And thereupon He continues, enforcing this very point, “For as the Father has life in Himself, so has He given to the Son to have life in Himself.” And then He comes to the sight of His own glory, in which He shall come to judgment; which sight will be common to the ungodly and to the just. For He goes on to say, “And has given Him authority to execute judgment also, because He is the Son of man.” I think nothing can be more clear. For inasmuch as the Son of God is equal to the Father, He does not receive this power of executing judgment, but He has it with the Father in secret; but He receives it, so that the good and the bad may see Him judging, inasmuch as He is the Son of man.
Since the sight of the Son of man will be shown to the bad also: for the sight of the form of God will not be shown except to the pure in heart, for they shall see God; that is, to the godly only, to whose love He promises this very thing, that He will show Himself to them. And see, accordingly, what follows: “Marvel not at this,” He says. Why does He forbid us to marvel, unless it be that, in truth, every one marvels who does not understand, that therefore He said the Father gave Him power also to execute judgment, because He is the Son of man; whereas, it might rather have been anticipated that He would say, since He is the Son of God?
But because the wicked are not able to see the Son of God as He is in the form of God equal to the Father, but yet it is necessary that both the just and the wicked should see the Judge of the quick and dead, when they will be judged in His presence; “Marvel not at this,” He says, “for the hour is coming, in the which all that are in the graves shall hear His voice, and shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation.” For this purpose, then, it was necessary that He should therefore receive that power, because He is the Son of man, in order that all in rising again might see Him in the form in which He can be seen by all, but by some to damnation, by others to life eternal.
And what is life eternal, unless that sight which is not granted to the ungodly? “That they might know You,” He says, “the One true God, and Jesus Christ, whom You have sent.” And how are they to know Jesus Christ Himself also, unless as the One true God, who will show Himself to them; not as He will show Himself, in the form of the Son of man, to those also that shall be punished?
Source: On the Holy Trinity (New Advent)