Judas saith unto him, not Iscariot. — That he was “not Iscariot” is mentioned to distinguish him beyond all possibility of confusion from him who had gone out into the darkness, and was no longer one of their number (John 13:30). He is commonly identified with “Lebbæus whose surname was Thaddæus” (comp. Note on Matthew 10:3), and was a brother or son of James (Luke 6:15).
How is it that thou wilt manifest thyself unto us, and not unto the world? — The word “manifest” has brought to the mind of Judas, as the word “see” had to the mind of Philip (John 14:7), thoughts of a visible manifestation such as to Moses (Exodus 33:13; Exodus 33:18), and such as they expected would attend the advent of the Messiah (Malachi 3:1). But it was contrary to every thought of the Messiah that this manifestation should be to a few only. His reign was to be the judgment of the Gentiles, and the establishment of the Theocracy.
The words rendered, “How is it that...?” mean literally, What has happened that...? The words of our Lord, speaking of His manifestation, take Judas by surprise. He wonders whether anything has occurred to cause what he thinks a departure from the Messianic manifestation.