Like any missionary, except one who preaches out of the book of (
Karl) Marx.
Basically, any communist in your workplace or college.
They
believe in overthrowing the superior western system of capitalism, and replacing it with what is essentially surfdom - basically,
people working in the fields and factories all day for virtually no personal gain.
They are annoying, and like most cultish preaching missionaries, they speak some real non-sense, and are hard to get rid of.
And like Scientologists, they will make your life a living
hell if they find that you have anything against them.