Interesting case.  On the one hand, why should the baker be forced to make a cake for anyone he doesn't want to?  He owns the bakery.  But on the other hand, if he owned a restaurant and pounded up a 'No blacks' sign above the door, then claimed that it was because of his religious beliefs, should that be acceptable?  Where does it end?

That aside, would you really want to eat the cake personally baked by the guy who would fight you all the way to the supreme court?  Yum!