During Karl Marx's life, Germany was the supreme industrial superpower of the world and Marx had no reason to believe that this would ever change. He assumed that Germany would continue to be the center of all technological and social progress in the world and that the rapid technological development of the Industrial Revolution would continue and German society would soon become a post-scarcity society where technology has eliminated all inequality and automated all labor and this society would naturally gravitate towards communism as things like class and money become irrelevant, and religion would also gradually fade from society as the end of the class struggle would theoretically do away with any need for religion's pacifying force to quell the impoverished masses. Obviously, none of these things happened and the events of the 20th century were probably utterly unlike anything Karl Marx could have anticipated, so the man effectively devoted much of his life to laying out the groundwork for a society that would never be. When it comes to Marx, what is really most relevant about his work for people in the real world today is the fundamental stuff about workers seizing the means of production; all of his theories about what kind of society would be built after the revolution are just pure academic conjecture from a 19th century German academic with a very 19th century German view of the world.