If we extend unlimited tolerance even to those who are intolerant, if we are not prepared to defend a tolerant society against the onslaught of the intolerant, then the tolerant will be destroyed, and tolerance with them. [...] for it may easily turn out that [the intolerant] are not prepared to meet us on the level of rational argument, but begin by denouncing all argument; [the intolerant] may forbid their followers to listen to rational argument, because it is deceptive [...] We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant.
We should claim that any movement preaching intolerance places itself outside the law and we should consider incitement to intolerance and persecution as criminal, in the same way as we should consider incitement to [other crimes] as criminal.
I agree, I think it's good to have a discussion, and polite disagreement is quite acceptable. But like you said, encouraging violence and hatred is not acceptable to me.