18 He that believeth in him is not judged. But he that doth not believe, is already judged: . . .
Chrysostom: There follows something about the punishment of unbelievers, to warn us against flattering ourselves that we can sin with impunity. Of the unbeliever He says, ‘he is judged already.’ – But first He says, He that believeth on Him is not judged. . . . But what if his life be impure? Paul very strongly declares that such are not believers: They confess, he says, that they know God, but in works deny Him [Titus 1:16]. That is to say, Such will not be judged for their belief, but will receive a heavy punishment for their works, though unbelief will not be charged against them.
Chrysostom: Disbelief itself is the punishment of the impenitent: inasmuch as that is to be without light, and to be without light is of itself the greatest punishment.
Or He is announcing what is to be. Though a murderer be not yet sentenced by the Judge, still his crime has already condemned him. In like manner he who believes not, is dead, even as Adam, on the day that he ate of the tree, died.
Augustine: The Judgment hath not appeared, but it is already given. For the Lord knows who are His; who are awaiting the crown, and who the fire.
Gregory: In the last judgment some perish without being judged, of whom it is here said, He that believeth not is condemned already. For the day of judgment does not try those who for unbelief are already banished from the sight of a discerning judge, are under sentence of damnation; but those, who retaining the profession of faith, have no works to shew suitable to that profession. For those who have not kept even the sacraments of faith, do not even hear the curse of the Judge at the last trial. They have already, in the darkness of their unbelief, received their sentence, and are not thought worthy of being convicted by the rebuke of Him whom they had despised. . . . For an earthly sovereign, in the government of his state, has a different rule of punishment, in the case of the disaffected subject, and the foreign rebel. In the former case he consults the civil law; but against the enemy he proceeds at once to war, and repays his malice with the punishment it deserves, without regard to law, inasmuch as he who never submitted to law, has no claim to suffer by the law.
18 . . . because he believeth not in the name of the only begotten Son of God.
Alcuin: In this name alone is there salvation. God has not many sons who can save; He by whom He saves is the Only Begotten.
Augustine: Where then do we place baptized children? Amongst those who believe? This is acquired for them by the virtue of the Sacrament, and the pledges of the sponsors.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. IV (London: Rivington, 1845).