Thank you for responding. The rule of thumb I aspire to (but am by no means a perfect example of) is always be respectful to the person, but only respectful to the ideas worthy of our respect. I have no problem with an argument which strongly and unambiguously opposes a hateful or patently false ideology or statement. However, making it personal by attacking the people that hold these views ultimately takes the focus away from the ideas they are espousing by making them the issue. This creates the risk we turn them into martyrs in the eyes of people that were previously on the fence, to say nothing of to their supporters.
Again, I would use the example of MLK. I can think of no instance where he personally attacked the bigots that were opposing him, but we can all think of countless speeches where he attacked the bigotry they advocated. Furthermore, he offered us a positive alternative to the bigotry. It is, of course, okay to say “I strongly disagree with the views of so and so…” But name calling, labeling, etc., are just ad hominem attacks. The fact that the attacks are for a good cause doesn’t change the fact we’re still engaging in a behavior we consistently and correctly criticize as a fallacy when others with whom we differ do it.