I am putting together a keepsake of my ancestors and a relative said of my great-grandfather: "He loves Saturdays and attends shul religiously.  After shul, he returns home to a nice lunch, takes a nap, and heads downstairs to argue his socialist views with his communist neighbors." 
I would like to put this into context and have tried to look into this, but would like to know if anyone can explain in a nutshell what the discussion at that time between socialists and communists in the Lower East Side in the mid 1920s.  Thank you so much.