I have been thoroughly enjoying a careful reread of Karl Kautsky’s much neglected Vorläufer des neueren Sozialismus, especially the second volume. The translation is known as Communism in Central Europe in the Time of the Reformation. Not a bad title, since Kautsky has no problem speaking about Christian and heretical communism. More soon, but for now an insight that goes well beyond both Marx and Engels:
The more radical a social movement, the more theological are its party words (p.221).
His immediate reference is the Reformation. Immediate political and economic terms were expressed as such – bread riots, protests against landlords, etc. But when a movement gained in breadth and strength, it sought deeper and more radical expression. This is where it became thoroughly theological.