Difference between a terrorist and a terrorist sympathizer.
The FBI's website defines domestic terrorism as: Violent, criminal acts committed by individuals and/or groups to further ideological goals stemming from domestic influences, such as those of a political, religious, social, racial, or environmental nature.
Yeah if they are using actual violent acts then they probably need to be reported. If they are just very opinionated then that isn't terrorism. Why? Do you know someone or just asking for a friend?