"for Marx, the state was only the expressionn of the interests of the ruling ( capitalist) class...."

Tug the Cox, not really the place to get into a dialectical discussion. The issue of state (or State) control was one of reasons for the split between Bakunin and the anarchists and the Marxist faction, which let to the expulsion of Bakunin and his followres from the International. Regarding this, Peter Marshall, in his 'Demanding the Impossible - A History of Anarchism', states: "According to Guillaume, those who followed Marx in advocating the ownership of collective property by the State began to be called 'State' or 'authoritarian communists', while those like Bakunin who advocated ownership directly by the workers' associations were called 'anti-authoritarian communists', 'communist federalists' or 'communist anarchists'".

The battle of words and ideas between Bakunin and Marx and Engels was a bitter one. But, in the end, it centred around Bakunin's belief that the State had to be eliminated entirely, while Marx advocated State socialism. History shows that Bakunin's warnings against "centralism, State socialism, and the dictatorship of the proletariat" were correct.