Personally I don't see the problem with them not making the cake. If the guy said "aghh you're gay I can't serve you" that would be one thing, but every business can choose what services they do and don't provide so if a gay marriage cake isn't on the menu why should government intervene to force them to put it on the menu?
If I wanted to get my buddy a cake and I told the baker I wanted it to be a naked woman cake and say "Happy Birthday You Fucking Cunt" on it, I'm sure a ton of bakers would refuse because it goes against their taste, so I don't see how that's any different than someone refusing to do a gay marriage cake because it goes against their religion.
Liberals don't know the slippery slope they're getting into. If they create rules and laws stomping on the religious rights of white Christians, those same laws can and will be used against Muslims (the left's pet victim of the month). I'm agnostic, I don't have a horse in the religion race, but there's definitely a war going on against white Christians.