I wouldn't say Marxism is incompatible with dualism for example, yes Marx heavily focuses on the material struggle, but interpreting the theory in a dualist sense doesn't really change its implications. Wealth really matters because of the way it makes us feel, the experiences it enables, not because of some inherent value. If being poor didn't feel bad, nobody would have a problem with it.

You can make ethical arguments based in reason.

Come on, I'd love to hear some, also the stakes are still up if you can give me a rational argument why killing is wrong.