Bakers don't need to put 'two plastic men' on a wedding cake. They can bake the cake and the couple can put the figurines on top. No one need know its a cake for a gay couple. I don't think that is relevant, anyway.
No matter what, you can't discriminate. It doesn't matter what your beliefs are - you cannot refuse to serve a black person, no matter how you feel about black people - so why should you be allowed to refuse service to a gay person, or a gay couple?
This is a tough one for me. The conservative part of me feels a business should be allowed to decide who they do or do not want to serve. The anti-bigot in me feels they should not be allowed to refuse service to anyone for irrational reasons, such as hating them just for being gay or black or country bumpkins.
Except we are focusing on mom and pop operations, which appeals to the conservative streak.
But what if a phone company like Verizon decided to stop serving blacks and Jews? Should they be allowed to do that?
Sure, we could argue it would be a huge economic mistake for them to give up so much business, but that just means we would be arguing it is okay to discriminate against really tiny minorities who have virtually no economic or political voice. It doesn't seem like that is the way to go.
Going the other direction, if a mom and pop bakery is the only bakery in town, do we just say, "Eat shit or make your own cake" to anyone they choose not to serve?
Like I said, this is a tough one.