13 By all means there is a sense, a true and strong sense, if somehow we can grasp it, in which “the Father judges not any man, but has given all judgment to the Son.” For this is said because none will appear to men in the judgment but the Son. The Father will be hidden, the Son will be manifest. In what will the Son be manifest? In the form in which He ascended. For in the form of God He was hidden with the Father; in the form of a servant, manifest to men. Not therefore “the Father judges any man, but all judgment has He given to the Son:” only the manifest judgment, in which manifest judgment the Son will judge, since the same will appear to them that are to be judged.
The Scripture shows us more clearly that it is the Son that will appear. On the fortieth day after His resurrection He ascended into heaven, while His disciples were looking on; and they hear the angelic voice: “Men of Galilee,” says it, “why stand ye gazing up into heaven? This same that is taken up from you into heaven, shall so come in like manner as you have seen Him going into heaven.” In what manner did they see Him go? In the flesh, which they touched, which they handled, the wounds even of which they proved by touching; in that body in which He went in and out with them for forty days, manifesting Himself to them in truth, not in falsity; not a phantom, or shadow, or ghost, but, as Himself said, not deceiving them, “Handle and see, for a spirit has not flesh and bones, as you see me have.” That body is now indeed worthy of a heavenly habitation, not being subject to death, nor mutable by the lapse of ages.
It is not as it had grown to that age from infancy, so from the age of manhood declines to old age: He remains as He ascended, to come to those to whom He willed His word to be preached before He comes. Thus will He come in human form, and this form the wicked will see; both they on the right shall see it, and they that are separated to the left shall see it: as it is written, “They shall look on Him whom they pierced.” If they shall look on Him whom they pierced, they shall look on that same body which they struck through with the spear; for a spear does not pierce the Word.
This body, therefore, will the wicked be able to look on which they were able to wound. God hidden in the body they will not see: after the judgment He will be seen by those who will be on the right hand. This, then, is what He means when He says, “The Father judges not any man, but all judgment has He given to the Son,”— that the Son will come to judgment manifest, apparent to men in human body; saying to those on the right, “Come, you blessed of my Father, receive the kingdom;” and to those on the left, “Go into everlasting fire, which is prepared for the devil and his angels.”
Source: Tractates on the Gospel of John (New Advent)