The difference between a St. Paddy's Day parade and a Nazi rally is primarily that the Irish as a whole do not espouse the wholescale massacre of all non-Irish, but also that it has very little to do with ideology (at least in my experience). Nazi rallies are for people who hate everyone that isn't an Aryan, St. Paddy's Day parades are for people who think that beer tastes better with green food coloring in it.

I recall perfectly well what the Spanish Inquisition did; recall, however, that until the rise of Protestantism, spurring the formation of the Inquisition, Spain, not England, was the nation most tolerant of Jews and Muslims in Europe. England kicked its Jews out more times than anyone except France. Everyone has done bad things in the past, and it would be a very hard call to make who's done the worst.