tomus - // If they'd have said 'we're not going to serve you because you're gay or you support gay marriage' that would have been discrimination.
They just said we're not going to do that particular design. If anything they discriminated against the cake. //
I think you are reaching for a defensive aspect to the bakers' behavior, which is not actually there.
Although none of us heard the exchange, it's perfectly clear that the bakers confirmed that their reason for refusing the order was firmly routed in the offence to their religious beliefs which they perceived as unacceptable, hence the refusal.
As I have said before, this is the third or fourth time - the bakers could have declined the order without reason, or simply made up a reason, too busy etc., in order to avoid giving offence to a customer and losing theirs, and their friends' and colleagues' business in the future, which would have made good business sense.
They preferred to pronounce from their very high horse, and paid the price for their arrogant bigotry.