Not every mention of Judaism
is associated with Hitler, so I'm not sure why you ask. Most of the times I hear Judaism mentioned, it is not in the context of Adolf Hitler. I think you're the first person I've ever heard draw a universal connection between the two.
As for Hitler, he is most famous (at least in America) for his violent hatred of the Jewish people, so it is likely that mentioning him will bring it to mind. I mean, what are we supposed to think of? Complaining that Hitler is associated with Jews seems like saying, "Good grief, every time I mention Picasso, people think of Cubist art!"