As Paul Hoffman's excellent book on Erdös, The Man who loved only numbers describes, The SF is the Supreme Fascist, the Number-One Guy Up There, God, who was always tormenting Erdös by hiding his glasses, stealing his Hungarian passport, or worse yet, keeping to himself the elegant solutions to all sorts of intriguing mathematical problems.
Another piece of Erdösese (other examples include "epsilon" for small child, "bosses" for women and "slaves" for men), his view of God as the Supreme Fascist is particularly pessimistic:
"The game of life, is to keep the SF's score low. If you do something bad in life, the SF gets two points. If you don't do something good that you should have done, the SF gets one point. You never score, so the SF always wins." - Erdös.
Erdös first began calling God the SF in the 1940s. "With so many bad things in the world, I'm not sure that God, should He exist, is good". He voiced approval for a novel, The Revolt of the Angels by Anatole France, which depicted God as evil and the Devil as benign.
Of particular note is the SF's book, transfinite in size, which "contains the best proofs of all mathematical theorems, proofs that are elegant and perfect". Thus the greatest praise one could receive from Erdös would be for him to describe your work as "straight from the book". He also observed that "You don't have to believe in God, but you should believe in the Book", illustrating his belief that the best mathematics wasn't just functional but beautiful.