Dialectics and class revolution according to Engels and Marx - both of them prescribe to the idea that society is eternally class-based and only through eliminating these classes (through revolution, purging and perpetual class warfare) and creating a society where there exists no desire for private property (i.e. contrary to Human nature in the long-term) can Humanity reach an ideal state of 'utopia' - it's like layered utopianism with a socioreligious twist, that intends to ultimately erase even the concept of 'money' as we know it as society becomes a collectivized mass all 'contributing' to each other through the larger state, erasing individuals as a whole in the process as individualism is contrary to the concept of the revolutionary class; the revolution is never actually "over", and is perpetual, meant to be global and ongoing and even if every nation flew a Communist banner, the revolution must perpetually continue until there exists no Human contrarian to the proletariat, which itself is vague and fluid, lacking real definition in modern times - Stalin preached a different type of thing called 'Socialism in One Country' and his opposition to Trotsky was rooted in the fact Trotsky was very fucking true-to-the-book and preached for global revolution and fostering civil wars all across the globe.
Concepts of practicality in Communist circles vanished long ago when they fractured along the lines of authoritarian and Marxist and began calling each other 'tankies' en masse and began parading around ideas of 'reform' and 'revision' in order to extinguish the public perception of Communism as a revolutionary mask concealing a generation of tyranny/class-based oppression, and in coming to the realization that the majority of what they believed was absolutely fucking impractical, the eventual idea set in that one must completely erode the pillars of reason and sense Western civilization existed on and make black white, up down, etc. etc. in order to completely subvert the concept of 'normality' and make what was abnormal to Westerners for generations, normal, so as to make the grounds "fertile" for actualized revolution and Communism - you could call this the 'academia' Marxism that started to take hold in the U.S. some 30-40 years ago - 'classes' became merged into the racial discussion due to the circumstances of American society particularly (and now Western society as a whole, really.)
I suggest reading State & Revolution by Lenin and Animal Farm by Orwell (the Manifesto & Das Kapital are obvious choices first.) in order to gain a grasp of what Communists actually perceive as the ideal path to revolution in the West - know your enemy, and know how absolutely psychotic they are; all the riots we're seeing are essentially textbook.