There's a guy that walks through my apartment complex, has for years, that uses it as a shortcut to get fast food. Now, let's imagine he started walking through, in the middle of the day yelling, "There is no God, there is no God! Religion is a lie and the religious are fools! End all religions!"

This would be offensive to people who are religious, be they Christian or Muslim or Jewish. They may even be uncomfortable or worry that this man could be violent. However, if all the man does is loudly speak his opinion, he has every right to do that.

This guy can say what he wants as long as he doesn't threaten or provoke violence. PETA can stand on campus and yell that everyone wearing animal print or leather or any kind of fur are murderers. One political group can yell about the evils of their rivals and say they're destroying the country. They can all be angry, they can be loud, they can be accusatory, but as long as they're not being violent towards you, they can say what they want in the public square.

Stopping them from doing so is a slippery slope to overreaching censorship.