Is it ever ok to call someone else a Nazi?

Incitement to hatred in a public domain might be something that can be investigated as to its intent - but to criminalise - and therefore to invite public vilification of people whose attempt to enforce their version of truth upon another-  reveals itself -  in a symbolic and frustrated attack - that has no intent other than to dump on the other and break communication in an appearance of triumph of being right - is to LOSE the opportunity to bring this very behaviour - and its associated mentality - into the light of awareness. Raising awareness may involve calling a stop to institutionalized or previously accepted  'cultures' of abuse - and law may have a place, but only if it is simply the backstop beneath a true culture of communication.

We feed and even become the thing we hate in our self righteousness - and unfortunately, the psychological insights that could have set us on a road to enlightenment are used for the same old mentality of god and devil, right and wrong, It is this mentality that deprives our mind of its wholeness and makes a blinkered and fearful fragmented approach to life that is not inherently necessary. There is a better way - and it is worthy of being discovered.
To attempt to use law - with the backing of the force of the State - to force people to be 'good' - or prevent them being 'bad' is just the same sort of mentality as that under the Nazi or any other tyrannical ideology - in that they who are sure they are right (because who they are fighting against are definitely wrong!) - feel fully justified in forcing their will upon others.
War is a breakdown of communication, but so is the use of communication as a mere manipulative device; a mask; a strategy of self interest at the other's expense.
As we do to our fellow man, we do to our very self. This may not seem true to a mind that uses truth to spin its own story - but it is inescapable. We know what judgement and blame brings forth. How about seeing what a true willingness to listen and learn brings forth?