Neither side in an argument can find the truth when both make an absolute claim on it.
"It ain't what they call you, it's what you answer to." - W. C. Fields
Sorry if that's too off-topic, but I believe it's remotely related to the topic:
I have seen people here in Germany flying the flag of the former East German communist dictatorship GDR. Usually, they are idiots. Nostalgics who had a nice youth in the GDR, but became victims of the economic transformation after Reunification 1990, now unemployed and so on.
Now there is nothing wrong with being nostalgic (who doesn't want the good old times back, sometimes? And of course you can have a good life, even in a bad system), and it is nothing necessarily wrong with being critical of our current system, or the way Reunification was handled -- but I believe you can well hold these opinions, without at the same time justifying Berlin Wall, persecution of dissidents and shooting orders at the border. But many mix personal nostalgia with political revisionism. The latter makes them idiots.
Now I don't want to go into the topic of people flying black-white-red. They are idiots anyway, by default. :P
"Not learning from mistakes is worse than committing mistakes. When you don't allow yourself to make mistakes, it is hard to be tolerant of others and it does not allow even God to be merciful."