The key employee anti-discrimination law is the Title VII of the Civil Rights Act of 1964 which prohibits employers from discriminating against applicants and employees on the basis of race, color, religion, sex, and national origin - but not political affiliation.
It’s the Democratic party.
State, federal or Civil Rights Act or not, it's illegal.
California Labor Code 1101 and 1102 LC expressly forbids it, including retaliatory actions (which is a much lower bar than firing).
In California, being passed up for promotion or being discriminated against in ANY way as a result of your political beliefs or activities is illegal.
I guess the question now is, was there a general principle behind that, or are we just cool with Stalinism now?
Believe it or not it’s completely legal to fire someone in California for going to a black lives matter protest or a conservative conference.
[1] https://www.shouselaw.com/ca/labor/harassment/political-reta...
I think the moment company starts taking heat on internet/talk shows/etc. for "employing fascists" that employee will get booted out for poor performance/HR complaints/staff cuts/etc. Or somehow he will resign himself ("no-no, we didn't force him out" company spokesman said in a statement).
On the other hand, certain beliefs of certain religions would be potentially incompatible with workplace discrimination law, including law that protects other protected classes. So it gets a little murky. One thing you can say is that if you have a religious belief that isn't causing you to bother other people, that's protected in the U.S.
You are correct about political beliefs, though. At least as far as I can find, political affiliation is not protected. But even if it were, this would necessarily not cover all possible political beliefs, for the same murkiness reasons as above.
California has strict protections, including protection from retaliation.