Complex sentence: Lenin believed that the vanguard party could initiate policies in the name of the working class even if the working class did not support them, since the vanguard party would know what was best for the workers, since the party functionaries had attained consciousness.
Split into simpler sentences: Lenin believed that the vanguard party could initiate policies in the name of the working class even if the working class did not support them. The vanguard party would know what was best for the workers because the party functionaries had attained consciousness.