I find the trend in our society that "if you say anything I disagree with, everything you say is invalid" to be very disturbing (the corollary of "if you agree

I find the trend in our society that "if you say anything I disagree with, everything you say is invalid" to be very disturbing (the corollary of "if you agree with something important to me then I will forgive much, if not all, bad behavior" seems to be true as well). McCarthyism in any form is evil, yet people will hold up their own beliefs and say "this is the only right way to believe". I fear what this will do to important rights like free speech. It doesn't matter if you have the "right" if cultural pressure squashes any ability to use it.