It has to cut every which way, though -- Muslim service workers here, and in the UK and Canada, also cannot be allowed to refuse service to people buying alcohol or pork, or traveling with dogs, because of their religious hang-ups. Right? If the Catholic or evangelical at the pharmacy can't refuse to sell special pills to whores, then it applies across the board; whether you're Muslim, Orthodox Jewish, Wiccan or whatever, and your beliefs prevent you from performing the basic functions of your job, you need to find another fucking job.
It is not the responsibility of a customer who just wants to buy some booze, or a wedding cake, or birth-control pills, to concern themselves with what should be people's personal, private beliefs. They want to come in, purchase something, and go home. There is no need for the merchant, or his minion, to infect what is entirely a transactional relationship. Most of us wouldn't put up with that sort of treatment from our friends, and we're supposed to let some asshole suffuse a simple purchase with his feewings? No dice, pal.
As Ed points out, racism really is more about social standing than anything else. But where it intersects with the world of commerce, especially in a chronically depressed economy, there are now powerful built-in disincentives to this sort of hare-brained bullshit. Businesses simply cannot afford to lose any customers at all, especially over something stupid.