It seems like we are well into the concern-troll phase of the cake-pizza-flower wars/freedom movement, which one might call either an organized retreat or a fall back to guerrilla insurgency in the all but lost battle against gay marriage. Because really, a lot of this is not that complicated. If you ask a baker to bake a cake that says “God hates gays” and they refuse, that’s not an imposition on your religion – unless you’re a complete moron.
Similarly, demanding a Jewish baker bake you a swastika cake and having them turn you down is not a denial of your free speech rights. Cake is not speech, even under the living constitution. And to get closer to the mark, I think if a gay couple went to a baker and asked for a wedding cake with two tuxedo-clad men at the top of the cake sodomizing each other, I suspect that few people would say the baker was outside his rights declining to bake that cake. (Jonathan Turley, who in addition to his other virtues has made something of a career out of what you might call the higher concern troll, makes the whole thing a lot more complicated than it should be in this piece in the Post.)
The fairly straightforward issue here is that if you are refusing people service based on their identity, especially if they are fast becoming a protected class along the order of racial and ethnic and religious minorities, that it is a problem if you deny a gay couple the same service that you would provide to a straight couple. To give the pizza example, the pizzas do not become gay because they are being catered at a gay wedding (who orders mall pizza for their wedding?)
Same with flowers. If you won’t send the same floral arrangement to a gay wedding as a straight wedding, that’s a problem. On the other hand, if just hypothetically, a lesbian couple wanted an elaborate floral arrangement symbolizing a graphic sex act, yeah, I think the florist can turn you down, just as I imagine it’s obvious the florist could turn down a hetero couple in a comparable situation.
Need more help? A black baker refusing to bake a cake for a white person because of centuries of discrimination? Not okay. A black baker refusing to bake a cake celebrating the KKK? Okay.
The closest I think you get in cases such like these, is that presumably the traditional man and woman statuettes at the top of the cake are replaced with two men or two women. But again, I think this is well within the conceptual framework of providing the same service to different people.