Sorry - it is not discrimination to ask to be served in a store open to the public.  As someone else said - if you don't want to deal with the public, don't go into business serving the public.  I am really tired of the far right "christians" trying to take over the representation of Christianity - their version is perverse and the antithesis of what Jesus taught.  I hope real Christians (the ones who actually practice what Jesus preached) step up and reclaim the mantle of Christianity.