A socialism based on idealism might consider its ready-made starting point in the question of Plato’s Cave: man must achieve not only economic liberation but a larger liberation from the inherent ‘exploitation’ of his limited consciousness. We can see in (mostly decayed) Christianity the dilemma of ‘spiritual’ modes: does religion liberate man or bind him in a controlled phenomenal realm? Is he a prisoner according to Platonic thinking.
More on this some other time. But the reality of Marxist realizations were always an exploited ‘material’ dumbed-down mental state open to a new form of controlled consciousness….
Man’s spiritual beliefs mostly end in superstitions as he wagers this thought against the noumenon and the unknowns behind the veil of the ‘phenomenon’.
Christianity claims to deal with all this for man, free of charge. It does nothing of the kind and (it has a long and varied history, mostly in decline) passes from the mysterious starting point into a state-controlled form of domination and in addition the unknow larger exploitation in the obscurity of the ‘unseen’.
Update: I will have to pass for the nonce on the rest of this interesting essay with a useful set of books listed at the end. The gulf between hoary transcendental idealism and William James is a challenge to a new synthesis…Marx attacks idealism at the point where it becomes a reactionary factor in the wake of the reactionary Hegel. But there is no reason that socialism has to attack idealism any more than physics should reject mathematics as idealist. Marx wanted philosophy in a practical form related to economic radicalism. Attacking idealism is a dated battle now