To quote Richard Stengal in the 24th Jan issue of Newsweek,
"Mere advocacy" of any doctrine, however violent, does not violate the First Amendment. And that makes sense. Words don't kill people; guns do. In an open and free society, we don't police speech, but we do police those who violate the law by committing violent acts.

Hm seems to make sense, but doesn't seem to be an accurate portrayal of the US.