Throughout the book of Bamidbar there are long list of misdoings: the longing for the “good old days” in Egypt, despising the Manna given by G-d and demanding instead meat, the report of the spies, the rebellion led by Korach against Moshe and Aaron’s authority. On the surface these are a variety of sins, in reality they all come back to the same issue – incessant complaining.
As a result of these complaints, the generation that left Egypt was punished, doomed to die in the desert and not enter the land of Israel. This is puzzling as that which would seem to be a much more severe sin, idolatry in the context of the sin of the Golden Calf, was ultimately forgiven. Why is it that complaining is worse than idolatry?