He preached ignorance based upon his lack of understanding about how markets work, where the advent of capitalism and resulting market liberalisation were heading, etc. One of the reasons why communists feared socialism was because they knew it made them irrelevant, and progressivism was entirely over their heads.
As for violence, there was the Bolshevik Revolution, the Great Purge, the internal carnage of North Korea, the Cultural Revolution, the Killing Fields, the treatment of political dissidents in Cuba and elsewhere, and the general presence of state-sponsored mass murder in every society which has experienced communism.
As I pointed out, those authoritarian ventures are far from the "pure" idea of communism. Marx never preached, supported, or would have condoned them - nor did Engels, Kropotkin, Owen, Kautsky, Plekhanov, Bakunin and the rest. Modern communists are of the sentiment. Cohen, Zizek, Wolff, and Chomsky being the most noteworthy communist scholars, all of which stand in stark opposition to the violence and authoritarianism of Russia, China, Korea, and to a lesser extent, Cuba.
Nothing outside of the pitiful Marxist-Leninist literature condones what you describe. Instead what you'll find is the most radical and holistic expression of democracy. Communism, though its intellectual heritage is mostly found in socialists, preaches the disintegration of oppressive institution (usually by mass action), not the state terror you fail to understand.
Face it, you have nothing. You try to discredit communism by pointing to the early stage of its development, but only serve to show an inability to comprehend the complexity of these situations. You try to show that we're violent, ignorant and the like, no? Well, I welcome you to do so. The Great Leap Forward, "socialism from above", these things are not a refutation of communism.