If I were a painter who specialized in portraits, and a potential customer came to me and said, "I want you to paint my portrait, and here's the picture I expect you to paint: In my portrait, I'll be sodomizing a 4-year-old child at the same time I'm shooting a police officer. Since you advertised you paint portraits, I'm sure you'll do this for me, won't you?"
Am I required by law to paint what this customer wants?