I like to poke around the state and federal statutes when I have nothing better to do. Try searching for the word “communist” in your local states legislation. In Texas you can’t be on the ballot or be appointed to an office if you are a “communist”
(b) A person may not hold a nonelected office or position with the state or any political subdivision of the state if:
(1) any of the compensation for the office or position comes from public funds of this state or a political subdivision of this state; and
So, thought crimes aside, the most interesting thing is that being a communist can have absolutely nothing to do with communism.
Sec. 557.021. DEFINITIONS. In this subchapter:
(A) by force or violence; or
(B) by unlawful or unconstitutional means and replace it with a communist government.
(2) "Department" means the Department of Public Safety of the State of Texas.
(3) "Government" means the government of this state or any of its political subdivisions.
Are you a forceful or violent revolutionary? Then you are a commie! Although peaceably replacing the government with a communist government seems ok. As does forcefully going after the Feds, just not the state or local governments.