Jesus sets His death in contrast to theirs. He is going but they will die in their sin. He uses the singular sin and not “sins.” Why? Perhaps to indicate the essence of sin and not the individual acts of it (Ezekiel 3:19); or perhaps to emphasize that one particular sin above all others: that of unbelief (Heb 3:12).

Ezekiel 3:19  But if you do warn the wicked man and he does not turn from his wickedness or from his evil ways, he will die for his sin; but you will have saved yourself.

Heb 3:12  See to it, brothers, that none of you has a sinful, unbelieving heart that turns away from the living God.

The ultimate horror and disaster, especially to the Jew who has been taught in these matters, is to die without having one’s sins repented and atoned for. Jesus had offered them His grace, which they rejected, and now He changes tactics and shows them what will happen if they don’t accept.

“look for me” = The Jews had always sought the Messiah, but there would come times when they would seek Him even more desperately than they could have imagined. They thought they had seen the worst, but ahead still lay the Jewish War when Rome would completely level Jerusalem and the Temple, the Holocaust when millions of Jews would be murdered, and many other atrocities against their people. The Jews have been seeking the Messiah for centuries, but they have been seeking Him too late: He has already come; and not as the Deliverer in the physical realm, for whom they looked, but as the Redeemer in the Spiritual realm. Bernard calls their seeking “the search of despair.” Edersheim mourns that “These many centuries has Israel sought its Christ, and perished in its great sin of rejecting Him. (Life and Times II, 170) The greatest tragedy of Judaism today is stated in John 1:11.

John 1:11  He came to that which was his own, but his own did not receive him.

“you cannot come” = unlike the criminal on the cross (Luke 23:39-43). What was the difference between these religious leaders and the criminal?

Luke 23:39-43  One of the criminals who hung there hurled insults at him: “Aren’t you the Christ? Save yourself and us!” But the other criminal rebuked him. “Don’t you fear God,” he said, “since you are under the same sentence? We are punished justly, for we are getting what our deeds deserve. But this man has done nothing wrong.” Then he said, “Jesus, remember me when you come into your kingdom.” Jesus answered him, “I tell you the truth, today you will be with me in paradise.”