The devil can cite Scripture for his purpose. - William Shakespeare
More specifically, from The Merchant of Venice (appropriate for some guy named Giuliani), Act I, Scene III:
ANTONIO: Mark you this, Bassanio,
The devil can cite Scripture for his purpose.
An evil soul, producing holy witness,
Is like a villain with a smiling cheek,
A goodly apple rotten at the heart
O, what a goodly outside falsehood hath!
Shakespeare had a source.