Politico has an article where the Anti-defamation League warns against using Hitler in the context of the current debates over gun safety. That's fine, but one does need an extreme example in any political argument, so I'll offer one: the Massachusetts Puritans. I'm reading Bernard Bailyn's Barbarous Years which is interesting. He observes that in the early days of the Bay Colony, when there was a raging conflict between Wheelwright and Hutchinson and the leaders of the colony (I'm sure that was covered in your history class--Anne Hutchinson being the first prominent woman protestor), the leadership took the step of confiscating all the arms possessed by the 60-70 people who supported the dissidents.
So instead of using a photo of Hitler, use one of the standard pictures of a Puritan, like John Winthrop, the man who used "city on a hill" before Ronald Reagan.