The idea of the inevitability of sin can sweeten some of the most bitter, even cruel verses in the Torah. It's tragic enough that Moshe, without whom there would be no Jewish people to enter the land, is denied entry into the land even after repeated entreaties. But when God begins to tell him, in chapter 31, of the ways that the Jewish people will rebel in his absence, rejecting everything he is trying so hard to pass on to them, it seems to cross the line from tragic into torture. Moshe was obviously anxious about the possibility that this would happen. Did God need to be so blunt?