He might be dead serious and really looking forward someday to the attainment of such a "higher phase of communist society"--but someday, and not now. Or he might (as Robert thinks) merely be making a nasty little inside joke: sneering that the "higher phase of communist society" in which the Lasallean program would be attainable is nothing but the millennium of Christian fellowship, as described in "Acts of the Apostles
[ cf Robert Waldmann Has an Interpretation of Karl Marx that Is New to Me... ]
I actually find it nice that the discussion is in play.
It is more important than whether or not Marx was sneering, or not sneering. Since the over-arching issue is how millennialism works in cultures. That is one of those SingularityMoments that keeps bothering me each time it's head crops up.
Hopefully we can arrive at a safe place where it is OK to talk about rational expectations of the future, without needing to make religious leaps of faith into the marketerringIsms!!!