As well as actually reading Marx's Critique of the Gotha Programme, he could also do with reading perhaps Lenin's best piece of work The State and Revolution, which provides a superb explanation and elaboration of one of Marx's most concise yet evocative works.
John describes "socialism" as the "transition on the road to communism." This is absolutely wrong.
Marx (below) and Lenin both used the term "socialism" pretty consistently to mean the first (or lower) phase of communism. Lenin explicitly used both terms interchangeably in order to reinforce that point.
John might find Marx described communism as representing the beginning of real human history, of true human civilisation.
Marx and Lenin both discussed explicitly that "between capitalist and communist society there lies the period of the revolutionary transformation of the one into the other. Corresponding to this is also a political transition period in which the state can be nothing but the revolutionary dictatorship of the proletariat."
Clearly, from a scientific materialist point of view, "socialism" cannot be at one and the same time the "transitional period" between capitalism and communism, two completely opposite social systems, and yet also be (the lower phase) of that new communism itself.
To confuse these massively different historic stages and processes is a mistake of epic proportions.