Penn Jillette and Islam

Penn Jillette has been quoted as saying:

Meaning, you won’t attack Islam because you’re afraid it’ll attack back ... Right, and I think the worst thing you can say about a group in a free society is that you’re afraid to talk about it—I can’t think of anything more horrific. [...]

I've read that during the McCarthy era, people were shouting from the rooftops that they were afraid to speak above a whisper.