Perhaps the sin Moshe committed, the sin that disqualified him from ever entering the holy land, was the sin of having a pre-9/11 mentality. What I mean by this is perhaps Moshe, as he stood at the rock, stick in hand, was unable to see the people for what they were. Instead of recognizing that the people in front of him were the children and grandchildren of the nation that had sinned so many times during the first eventful year in the desert, Moshe treated them as if they were their own parents. "Listen to me you rebels" he screamed. But these people were not rebels. They weren't the sinners who believed the spies, and supported Korach, and complained to Moshe for meat and cucumbers. These people were the offsrping of those sinners, and members of a new generation, the generation that was about to enter the Holy Land, and achieve their parent's dream. These children were better then their parents, unsullied by their sins, and deserving of different treatment. Moshe either could not recognize this or could not respond to it. Perhaps this inability to acknowledge the new facts, and to alter this thinking to suit them was the sin, the shortcoming, the failing, and the flaw that made it clear to God that Moshe was no longer the man for the job.