John 7:28

28.Jesus therefore exclaimed in the temple. He bitterly reproaches them for their rashness, because they arrogantly flattered themselves in a false opinion, and in this manner excluded themselves from a knowledge of the truth; as if he had said, “Youknow all things, and yet you know nothing.” And, indeed, there is not a more destructive plague than when men are so intoxicated by the scanty portion of knowledge which they possess, that they boldly reject every thing that is contrary to their opinion.

You both know me, and you know whence I am. This is ironical language. With the false opinion which they had formed concerning him, he contrasts what is true; as if he had said, “While you have your eyes fixed on the earth, you think that every part of me is before your eyes; and therefore you despise me as mean and unknown. But God will testify that I have come from heaven; and though I may be rejected by you, God will acknowledge that I am truly his own Son.”

But he who hath sent me is true. He calls God true in the same sense that Paul calls himfaithful

If we are unbelievers, says he, he remaineth faithful, he cannot deny himself,
(2 Timothy 2:13.)

For his object is to prove, that the credit due to the Gospel is not in the smallest degree diminished by the utmost exertions of the world to overthrow it; that though wicked men may attempt to take from Christ what belonged to him, still he remains unimpaired, because the truth of God is firm and is always like itself. Christ sees that he is despised; but so far is he from yielding, that, on the contrary, he boldly repels the furious arrogance of those who hold him in no estimation. With such unshaken and heroic fortitude all believers ought to be endued; nay, more, our faith will never be solid or lasting, unless it treat with contempt the presumption of wicked men, when they rise up against Christ. Above all, godly teachers, relying on this support, ought to persevere in maintaining sound doctrine, even though it should be opposed by the whole world. Thus Jeremiah appeals to God as his defender and guardian, because he is condemned as an impostor:

Thou hast deceived me, O Lord, says he, and I was deceived,
(Jeremiah 20:7.)

Thus Isaiah, overwhelmed on all sides by calumnies and reproaches, flies to this refuge, that God will approve his cause, (Isaiah 50:8.) Thus Paul, oppressed by unjust judgments, appeals against all to the day of the Lord, (1 Corinthians 4:5,) reckoning it enough to have God alone to place against the whole world, however it may rage and storm.

Whom you knew not. He means that it is not wonderful that he is not known by the Jews, because they do not know God; for the beginning of wisdom is, to behold God.