This is not refusal to simply serve a gay person. This is refusal to take part in a ceremony that goes completely against the religious convictions of the business. That is why we have a first amendment- to protect citizens from violating their religious beliefs. I would have a problem if the woman simply wanted some muffins that morning. That is not the issue. They wanted a particular item that the business did not provide....gay wedding cakes. You cannot force the baker to make gay wedding cakes!
If the Christian baker refuses on religious grounds to make a cake for a gay marriage, but agrees to make a wedding cake for the marriage of two divorcees, then the Christian baker is singling out one group to discriminate against, even though the Bible considers both groups sinful. The Bible also instructs Christians (”sinners”) not to judge others, as that is left only for God. Clearly, refusing to serve someone judged as “sinful” is in direct violation of Christianity. So, by peeling away the layers of hypocrisy, it’s clear that this isn’t about religion at all. It’s a clear case of bigotry. Jim Crow laws are illegal. If I have a religious belief against serving black people, should I be able to refuse on moral grounds?