Tremendously disturbing. The question in the marketplace should aways be "is your money good?" not "I don't like your face". The second is tremendously destructive to human liberty:

Kevin Drum: A Third of Republicans Think It’s OK to Refuse Service to Muslims: "I’m never quite sure how seriously to take survey results, and today Paul Waldman points to a new PRRI survey that I really, really don’t want to take seriously.... Thanks to a baker in Colorado, we’re all accustomed to the idea that conservatives think business owners should be free to refuse service to gay people if their refusal is based on religious belief. But apparently large numbers of them also think it’s fine to refuse service to Muslims, Jews, and African Americans.... Among Democrats, there’s apparently a single, smallish contingent—around 14-19 percent of the total—that thinks it’s OK to discriminate against anyone. But among Republicans, it varies. About 18 percent think it’s OK to discriminate against blacks compared to 47 percent who think it’s OK to discriminate against gay people. Jews and Muslims and atheists are in the middle.... There’s a liberal bloc that, on principle, thinks businesses should be allowed to discriminate however they want. Conservatives, by contrast, don’t think that. They endorse discrimination more or less strongly depending on how much they dislike the group in question. So to circle back to the beginning, I wonder how seriously to take this?...

A Third of Republicans Think It s OK to Refuse Service to Muslims Mother Jones