Kichwa, that does not worry me for this reason: weddings are events. They are not people. People are protected from discrimination. Not events or messages.
So if a racist religion denounces race-mixing as sinful (which I believe nowadays some do/might) a member of that religion should not be forced to take part in an event that inherently is about that very thing (race-mixing). They should not be allowed to refuse those same people service in any other scenario however where they cannot show such a link (besides freedom of expression scenarios). Now, if there is a religious rule that says serving people of a certain race or sexual orientation is a sin, in that case the the public interest to protect individuals from discrimination ought absolutely to supersede the religious/concientous-objection right. So refusing to sell them a cake would be a no-no in my books but if they requested a custom designed wedding cake where the baker's job is to create a message and such on the cake espousing views he himself disagrees with or even none, I'd support the KKK idiot's right to refuse.
The thing is, this is a question of a balance of rights/fundamental freedoms: conscience, religion, expression and freedom from discrimination. According to the SCOTUS (and to me) these are BOTH protected rights. You can't create a strict hierarchy that simply refuses to treat the right to conscientious objection as a real right based on one's own personal animus or contempt for religion or that particular religion. it would not be a freedom if it had to be vetted by those who don't share beliefs of the faith in question. I think the court struck a good balance. You can't just refuse to serve gay people but you can refuse to sell your services in support of messages or events you disagree with. I am comfortable with such a balance.