The phrase “he could piss off the Pope” is a common idiomatic expression used to describe someone who is exceptionally abrasive, arrogant, or difficult to deal with. It has been attributed to various individuals in different contexts rather than originating from a single famous source: 

OK–You are not Jesus, but you are Doctor Kildare !

Rule # 1: “First, do no harm.”

“Anyway you slice it, it’s still baloney.”