"This book you sold me doesn't teach me about black magic, " the now all-too familiar voice on the phone stated.  "Don't you witches do that stuff?"

"No sir, that's against our religion," I replied for the thousandth time.  "Our religion states: An it harm none, do as thou wilt."

"So how am I supposed to deal with black magic then?"

"By not agreeing to let it run your life, sir."

The conversation lasted 30 minutes.  During that time he continued to insult my religion with complete abandon.  Finally, I said:

"Sir, I would advise you to look to your own religion to deal with your problems, and stop using mine."

"What d'you mean, using?"

"Because, sir, you only wish to use our "magic"  for your own negative means, and are not truly seeking to respect the religion itself.  It is a religion sir."

"Fine then.  Well do you know any Warlocks?  There MUST be witches practicing black magic somewhere...."

I felt like I was in the worst Oh My Gods episode.
I didn't tell him that I had lost all respect for him, and that I hoped he didn't come back to my store.
He's a Quaker, and a Quacker.