Am I a Jew? - Am I likely to be influenced by Jewish prejudices and partialities? Am not I, being a Roman, likely to judge impartially, and to decide on the accusations without being blessed by the malignant charges of the accusers?
Thine own nation - In this Pilate denies that it was from anything that he had observed that Jesus was arraigned. He admits that it was from the accusation of others; but then he tells the Saviour that the charge was one of moment, and worthy of the deepest attention. It had come from the very nation of Jesus, from his own countrymen, and from the highest authority among the people. As such it demanded consideration, and Pilate besought him to tell him what he had done - that is, what there had been in his conduct that had given occasion for this charge.

Am I a Jew? - That is, I am not a Jew, and cannot judge whether thou art what is called the Christ, the king of the Jews. It is thy own countrymen, and their spiritual rulers, who delivered thee up to me with the above accusation.
What hast thou done? - If thou dost not profess thyself king over this people, and an enemy to Caesar, what is it that thou hast done, for which they desire thy condemnation?

Pilate answered, am I a Jew?.... This he said, in a sort of derision and contempt; who was not a Jew, neither by birth, nor by religion, and so had never imbibed any notions of their King Messiah, nor read anything about him; and knew nothing of his distinguishing characters and properties, by which he was described, and might be known; and therefore it remained, that what he had said, though not expressed, was not of himself, of his own knowledge or observation, but arose from some intimations and suggestions the Jews had given him:
thine own nation and the chief priests have delivered thee unto me; that is, the men of his nation, his countrymen the Jews, who best understood their own laws and books of prophecy; and what expectations they had formed from thence, concerning their king, and his kingdom; and the principal of the priesthood, who were accounted men of the greatest learning, piety, and integrity, they had brought him bound before him; they had entered a charge against him, and had delivered him up into his hands, as an enemy to Caesar, and a traitor to his government:
what hast thou done? as an occasion of such treatment, and as the foundation of such a charge; surely there must be something in it, or men of such character would never impeach a man altogether innocent, and one of their own country too!

Pilate answered, Am I a Jew? Thine own nation and the chief priests delivered thee to me: What hast thou done?--that is, "Jewish questions I neither understand nor meddle with; but Thou art here on a charge which, though it seems only Jewish, may yet involve treasonable matter: As they state it, I cannot decide the point; tell me, then, what procedure of Thine has brought Thee into this position." In modern phrase, Pilate's object in this question was merely to determine the relevancy of the charge.