Marxists are told that the role of the working class in the society of the advanced capitalist countries is diminishing as there are less manufacturing jobs and more jobs in service sector and the size of the working class is shrinking due to automation. Marxists in the so-called third world countries are often told that there is no working class as these countries depend on exporting row materials like oil and most of the manufactured goods are imported. We are told that the class struggle is not the main struggle in the society and therefore Marxism is becoming obsolete. What is your response?
These criticisms suggest that the critics have a very poor grasp of what Marx argued. In Marx's Capital, he focuses his analysis on the core relationship of modern capitalism, that between employer and employee in producing commodities for sale in markets. He explicitly includes BOTH "goods" and "services" when they take the form of commodities emerging from an employer/employee relationship in production. Therefore, that some modern economies display a transition from goods to services productions say NOTHING about the relevance of capitalism or Marx's critique of capitalism so long as the employer/employee relationship governs the production of the goods and services.
The same logic applies to the specific nature of the commodities (i.e. whether they are oil or other "raw materials"). Once again, if they are brought out of the ground, transported, more or less "processed" by means of enterprises whose organization of production is built on the employer/employee relationship, they are capitalist commodities and the workers engaged in producing them are what Marx meant by working class just as much as are workers producing capitalist commodities in the forms of manufactured goods, services, etc.
The problem in the US today is not that there are critiques of Marx and Marxism around; good critiques could and would stimulate debates, self-searching and thereby progress for Marxism (as good critiques do for any body of thought). The problem is that an entire generation of Americans has gone through a college and university system whose fear of Marx, Marxism, and Marxist professors precluded that generation from having proper instruction in Marx's theory. Their critiques - now that capitalism's contradictions have revived interest in Marx and Marxism - are thus poorly grounded (I am being polite) in a theory they have never had to learn.