Judas (not Iscariot) saith to him. It is not without reason that he asks why Christ does not cause his light to be imparted [1] to more than a few persons; since he is the Sun of Righteousness, (Malachi 4:2) by whom the whole world ought to be enlightened; and, therefore, it is unreasonable that he should enlighten but a few, and not shed his light everywhere without distinction. Christ's reply does not solve the whole question; for it makes no mention of the first cause, why Christ manifested himself to a few,' conceals himself from the greater part of men; for certainly he finds all men at first alike, that is, entirely alienated from him; and, therefore, he cannot choose any person who loves him, but he chooses from among his enemies those whose hearts he bends to the love of him. But he did not intend, at present, to take any notice of that distinction, which was far from the object he had in view. His design was, to exhort his disciples to the earnest study of godliness, that they might make greater progress in faith; and, therefore, he is satisfied with distinguishing them from the world by this mark, that they keep the doctrine of the Gospel. Now, this mark comes after the commencement of faith, for it is the effect of their calling. In other passages, Christ had reminded the disciples of their being called by free grace, and he will afterwards bring it to their recollection. At present, he only enjoins them to observe his doctrine, and to maintain godliness. By these words, Christ shows in what manner the Gospel is properly obeyed. It is, when our services and outward actions proceed from the love of Christ; for in vain do the arms, and the feet, and the whole body toil, if the love of God does not reign in the heart, to govern the outward members. Now, since it is certain that we keep the commandments of Christ only in so far as we love him, it follows that a perfect love of him can nowhere be found in the world, because there is no man who keeps his commandments perfectly; yet God is pleased with the obedience of those who sincerely aim at this end.

Footnotes

1 - "Pourquoy Christ fera que sa lumiere sera manifestee."

Judas saith unto him - This was the same as Lebbeus or Thaddeus. See Matthew 10:3. He was the brother of James, and the author of the Epistle of Jude.
How is it - Probably Judas thought that he spake only of his resurrection, and he did not readily see how it could be that he could show himself to them, and not be seen also by others.

Judas - The same as Thaddeus and Lebbeus, the brother of James, and author of what is called the epistle of Jude.
How is it - Or, how can it be - τι γεγονεν, what is to happen? - on what account is it? Judas, who was probably thinking that the kingdom of Christ should extend over all the earth, wonders how this can be, and yet Christ manifest himself only to his disciples and not to the world, John 14:19. To this our Lord, in a more express manner than he had done before answers: -

(7) Judas saith unto him, not Iscariot, Lord, how is it that thou wilt manifest thyself unto us, and not unto the world?
(7) We must not ask why the gospel is revealed to some rather than to others, but we must rather take heed that we embrace Christ who is offered unto us, and that we truly love him, that is to say, that we give ourselves wholly to obeying him.

Judas saith unto him, not Iscariot,.... This was Judas Lebbaeus, whose surname was Thaddaeus, the same with Jude the apostle, the author of the epistle which bears his name; and is said to be "not Iscariot", to distinguish him from the betrayer. The question put by him, Lord,
how is it, , which answers to , or , or with the Talmudists, "what is this thou sayest"; what is the meaning of it? how can it be? or what is the reason of it,
that thou wilt manifest thyself to us, and not unto the world? arises either from ignorance of what Christ was speaking, imagining he meant a spectre, or some apparition of himself after his death, which should be visible to his disciples, and not to others; and how this could be, he wanted to know; or from that national prejudice which Judas and the rest of the apostles had given into, of a temporal kingdom of the Messiah, the glory of which should be visible to all the world; and therefore he wonders that he should talk of the manifestation of himself, only to some, or from an honest hearty desire that the glory of Christ might not be confined to a few only; but that the whole world might see it, and be filled with it: or rather from his modesty, and the sense he had of his own unworthiness, and of the rest of the apostles, to have such a peculiar manifestation of Christ to them, when they were no more deserving of it than others: the question is put by him with admiration and astonishment; and as not being able to give, or think of any other reason of such a procedure, but the amazing grace of Christ, his free favour and sovereign will and pleasure.

Judas saith . . . not Iscariot--Beautiful parenthesis this! The traitor being no longer present, we needed not to be told that this question came not from him. But it is as if the Evangelist had said, "A very different Judas from the traitor, and a very different question from any that he would have put. Indeed [as one in STIER says], we never read of Iscariot that he entered in any way into his Master's words, or ever put a question even of rash curiosity (though it may be he did, but that nothing from him was deemed fit for immortality in the Gospels but his name and treason)."
how . . . manifest thyself to us, and not to the world--a most natural and proper question, founded on John 14:19, though interpreters speak against it as Jewish.