Well, how about religiously motivated hate speech? If I go around and tell people that they should die 'cause my imaginary friend doesn't like how and who they fuck, think I will stay free for long?
It depends, and this is strictly my amateur legal opinion that shall not be construed as legal advice; if they are simply saying you're subject to judgement by their imaginary friend or some universal balance such as karma then their speech is probably protected under the first amendment, however if they are directly calling for violence against you or anyone else then the government has something potentially substantial to act on rather than just ideas but even in this case there may be nothing a liberty minded government can do until somebody actually acts on it; a good example might be "inciting a riot" where a person can basically say whatever he pleases but if his actions lead to a riot that threatens public safety then he can be potentially charged with a crime and convicted if the state can prove that person did so with malicious intent.
It is worth noting that hate speech laws are themselves a slippery slope that threaten liberty because in some countries that takes things to an extreme just merely saying you don't like, not necessarily outright hate, something somebody does or a certain culture can be considered hate speech.
Liberty comes at the cost of security but fear not for we have the 2nd Amendment.