Maybe Christian owners of businesses should put up signs to indicate who they will refuse service to?
"NOTICE: We do not serve homosexuals, adulterers, revilers, liars, anyone who eats shellfish or animals with cloven hooves, anyone who works on the Sabbath, doesn't honor their parents, anyone who mixes cottons and polyblends, or menstruating women. Jesus might love you, but we sure don't. Have a nice day!"
Seriously, though. They should put up signs indicating who they refuse service to.