My interest in Marxism was not just political but intellectual as well -- those two were inseparable. It didn't cause me problems on a day-to-day apart from when the university management tried to alter my conditions of employment! I think in some ways I was very fortunate but the liberal ideology you write about is very much a real thing that has to be constantly interrogated. As for organizations, my IRL comrades in the trade union were essential but I think it is vitally important to not place oneself in a position where you are at legal risk (if organizations are illegal I would be cautious as whatever organizations exist are almost certainly monitored or infiltrated) but the internet can be a great resource. I also think a certain degree of intellectual independence is not the worst thing in the world as all too often organizational fidelity can come at the cost of your own thinking.