As I posted in another thread, this should be a common sense issue.
If the cake ordered by gays/same sex couples is indistinguishable from a cake ordered by straights/heterosexual couples that the baker normally makes, the the baker should have to complete the order. After all, the cake isn’t gay, and the artistry of the cake in no way endorses the gay lifestyle or same sex couples.
On the other hand, if the cake is not indistinguishable from cakes ordered by non-gay people such that it’s obvious the cake is for a gay event or could be considered an endorsement of same sex marriage or the gay lifestyle, then the baker should not have to make a cake to those specifications. That would violate the bakers rights of freedom of speech and religion.
The baker should have control of what types of cakes he is willing to make or not. The baker should not be forced to make a cake that looks like a penis if that is not on the menu of the types of cakes he makes,