This is all true, but we're comparing the rationality record between various creeds and not imagining how well one such creed would do in a vacuum.

Frankly, I'd rather not compare the rationality record between various unspecified creeds, at least here; that sort of thing has a way of taking over threads, and in its general form seems almost completely orthogonal to Catholic deconversion or anything related to it. This business about skepticism came up in the context of Marx's proximity to traditional rationality of the Dawkins/Randi school, particularly in terms of approach to atheism, and that's where I'd like to keep it.

Dawkins et al. seem to be skeptical in methodology: presented with a set of supernaturalist beliefs, their normal procedure is to look at the claimed evidence for them, look for replications or attempt to perform a replication if it's convenient, and proceed to deprecate the beliefs in question when they predictably fail. They do tend to be fairly apolitical (Penn and Teller notwithstanding), and I'm not even sure what a proper extrapolation of this methodology to the social realm would look like, but I am pretty sure it wouldn't start with a future history (sketchy though Marx's is) or a complete theory of class interaction. And I'm also pretty sure most Marxists wouldn't appreciate a Randi-style analysis of their own foundational beliefs.