It's very obviously the shared burdens civic (came with the Le Guin update, I think), which requires fanatic egalitarian. Plus materialist (philosophical materialism, duh, but also FALGSC) would make the most sense unless you're trying to do something weird like militarist space Posadists. (I like to put them in my games as a potential ally, along with weird spiritualist communist psychic space mushrooms.)

It even comes with a Russian advisor voice that calls enemies reactionaries and talks about the means of production.