As far as Google is concerned, you are the originator of that quote. It has no other instances of that series of words strung together in that order, at all.
Here is one of his quotes on moral relativism:
"If you depart from moral absolutes, you go into a bottomless pit.
Communism and Naziism were catastrophic evils which both derived from moral relativism.
Their differences were minor compared to their similarities."