For what reasons was Communism not viewed as a viable ideology in Russia before the Bolshevik Revolution?

Karl Marx, the famous theorist of Communism, had not believed that Russia was ideal for its emergence. This was because Marx thought the event that would usher in the worldwide socialist revolution would be the rising of the industrial working class. These people, who were becoming increasingly marginalized and alienated by industrial expansion, were known as the proletariat. The more industrialized a society was, the bigger and more politically volatile its proletariat would become. Eventually, Marx thought, the proletariat, which had "nothing to lose but their chains," would rise up and overthrow the bourgeoisie, or the class of factory owners and financiers that profited from their labor. 

Marx, and most orthodox socialist thinkers that followed him, did not think Russia was likely to witness such a revolution because it was not very industrialized. Russia was still a mostly agricultural country, with small peasant landholders and villagers who lived a lifestyle little changed from the manorialism that characterized medieval life in the rest of Europe. Marx generally thought of peasants as a conservative force, unwilling to forge a political alliance with the industrial working class. French peasants, he famously said, were as incapable of the class consciousness that was a precondition to communist revolution as "potatoes" in a "sack of potatoes." 

This was one of the breakthroughs of Vladimir Lenin, who argued that Russia and its people could be mobilized to revolution. Rather than a large-scale, simultaneous uprising of industrial workers, however, Lenin successfully attempted to foment a rebellion led by a cadre of radicals (the "Bolsheviks") who were organized through revolutionary groups known as "soviets." So the Bolshevik Revolution, in short, occurred despite the skepticism of orthodox Marxian thinkers.