Outside of your job, you can be as politically active as you wish. Nobody is saying you should stop all political activism.
But if i walk into a store intending to buy something, i don't want to be blasted with any political message or be asked to sign up for a rally or donate to some cause i don't care about.
And an employee should work on the job they are being hired to do, not spend work time undertaking political activism unless explicitly allowed by their boss (for example, your company may allow you time off for charity or such activities).
If, for example, your political view is that of communism, then you will have to suffer in silence in the USA while working for shareholders/owners of property. Or quit your job if you cannot stand it. What you can't do is use your job as a resource to push that view further than you could on your own.