Harry,
Aside from the historical realities (atrocities) and the inherent flaws of any totalitarian system, where you in YOUR home?
If so, YOU and nobodyelse decides what is in line or not.
Just ask them, if nazism is so fine, why they screwed up in winning WWII.
Why, for about 40 years the remaining germans were not the most welcomed guests in the rest of Europe.
And explain them, that if nazism would be reinstated, many of the modern followers would end up in their own camps as antisocial elements.
Remember, not only jews were exterminated.
And, if you are in the educating mood, send them on a trip to auschwitz.
That's the cure.