Notice I didn't say anything about forcing a person to do anything. I said that hiding behind your religious beliefs is a crock of shit. Unless you are asking every customer if they've ever cheated on their spouse, ever been divorced or ever worked on a Sunday then you are cherry picking what parts of your religion you will use to deny someone service because you are offended by who they love.
Chi-fil-A is closed on Sunday. It is the founder's sincere religious belief that his employees should follow the Biblical proscription about working on the Sabbath. But being closed on Sundays denies everyone service that day. No one can complain because all of the public is affected the same.
But refusing to seat a gay couple in your restaurant because their existence offends you is different. You are denying them service with out cause. If you seat everyone but Jews at your restaurant because you think the Jews killed Christ you are applying your interpretation of your religion to discriminate. It is not now about your religious beliefs - it is about how offended you are that these people exist. What is different about that and denying to seat a mixed race couple?
The fact that you are offended by someone's political beliefs does not mean you can refuse them service on that basis. One is protected speech, the other is denying service to a person because they offend you. I thought that was settled at that Woolworth's lunch counter...