You may decline to serve for reasons not covered by the law.  In this case, the law takes precedence.  The baker could have said, I don't like the color of your shirt, so I'm not serving you.  But he specifically said I am not serving you because of your status.  He wanted to make an issue out of it.  If he had served the couple, his religious beliefs would still be intact, and we would not be having this conversation.  Serving someone does not change internal beliefs.  It's in the outward expression of those beliefs that discrimination becomes the issue.  For instance, let's say I have a business, and I don't like Christians.  I am entitled not to like anyone, but if they come into my business, I am required to serve them.  So, you DO NOT have to like gay people in any way (though I don't know why you wouldn't), but, if you have a business license, you have agreed to follow all applicable laws.