I feel like I understand communist theory pretty well at a basic level, and I believe in it, but I just don't see what part of it requires belief in an objective world of matter. I don't believe in matter and I'm still a communist. And it seems that in the 21st century most people believe in materialism but not communism. What part of "people should have access to the stuff they need to live" requires believing that such stuff is real? After all, there are nonmaterial industries and they still need communism. Workers in the music industry are producing something that nearly everyone can agree only exists in our heads. And they're still exploited by capital, despite musical instruments being relatively cheap these days, because capital owns the system of distribution networks and access to consumers that is the means of profitability for music. Spotify isn't material, it's a computer program. It's information. It's a thoughtform. Yet it's still a means of production that ought to be seized for the liberation of the musician worker. What does materialism have to do with any of this?
We are talking about survival and prosperity for all, in a context unlike that for which our perceptions have evolved. When it comes to the threats of civilisation, like "Am I going to make enough money for rent", our brains are poorly equipped to handle that situation. Just as a fish is poorly equipped to survive on land. It is in the new context of the civilised world that we must begin using our power of reason instead of relying on nature's instincts.