The problem is not that you are outnumbered, the problem is that your culture is too low compared to the other civs' tourism. The Order civs are producing so much more awesome art than you that your people think their system is obviously superior and/or your culture is so poor that they can't resist enemy propaganda.
And Order is not necessarily supposed to represent soviet style communism. The ideologies in ciV are supposed to represent multiple -sometimes idealistic- interpretations of 19/20th century ideologies. Think Democratic Socialism instead of Stalin burning orphans for tank fuel.
It appears that the combined tourism of a given ideology is weighed against the combined culture of those of other ideologies. Could be wrong, just going from the empirical evidence.
Speaking only from gameplay experience and without looking at the code, it appears to me that the combined tourism of
those civs that have more tourism than you have culture is used to calculate ideological pressure. If you're the only Freedom civ and there are four Order civs that each have slightly less culture/tourism than you,
their public opninion will suffer and yours won't be affected even if their combined tourism/culture is higher than yours.