Why should a baker be forced to bake a wedding cake for a gay couple if he's against same-sex marriage?
The answer is simple: If you offer a service to the public at large, you shouldn't be able to make a distinction because of your religion, your preferences or your ethics. Why? Because it's not about you.
Of course, you should be able to exercise your religious rights when it's just about you. No one is forcing you to marry someone of the same sex, but what business of yours is it what someone else decides to do? You won't be eating dinner with that same-sex couple when they come home from work. You won't be sharing their bed. You won't be cleaning their cat's litter box, taking their kids to school, washing their dishes or paying their hospital bills. You won't be reaping the benefits of that marriage - the love, the retirement plan, the vacations spent together - and it's not your responsibility. Which is to say, you don't get a say.
Because it's not about you.
Those actions only become "about you" when you engage in them yourself, when they become an integral part of your own life. That's the distinction.
If you're serving the general public as a businessperson, the service you provide is not about you, either. That service is provided for your customers. It's about them. Hence the old saying (too often ignored these days) that the customer is always right. That saying doesn't come with a qualifier like "as long as he's a straight, white, Protestant, Bible-believing male who roots for the Dallas Cowboys." It stands on its own, just as the money exchanged in any such transaction stands on its own. It's legal tender for all debts public and private. Says so right there on the currency. If the money doesn't discriminate, why should the service? It's a two-way street.
Here's the good news: If the service is about the customer, the money is about you, the merchant. You get to use it to buy school supplies for your kids, take a vacation with your spouse, buy cat litter for your feline friend, and so forth. Is that really so bad? You worry that someone else's same-sex wedding is damaging your marriage in some nebulous, undefined way, but isn't that money actually affecting your marriage far more tangibly and directly? And in a good way!
And you shouldn't worry about churches being forced to perform weddings for same-sex couples, either. That's a different slice of cake altogether. The distinction is simple: Unlike businesses, churches aren't offering their services to the general public. They're offering them to people of their own faith because, by definition, a church is built on moral and doctrinal agreements among members of the same faith.
Religious institutions such as churches, mosques and temples wouldn't exist without the faith to which they're attached. It's their fundamental raison d'etre. The same cannot be said for businesses owned by Christian, Muslim, Wiccan or Buddhist owners. They aren't in business to spread or facilitate their faith; they're in business to make a living by serving the general public. If their religion conflicts with their ability to provide the service they're offering, they should find another line of business - or, if they prefer, another religion. The choice is theirs.
This is, in fact, exactly what an Alabama judge decided to do: To avoid issuing licenses to same-sex couples, he decided to stop issuing licenses altogether. According to the judge, the law states that counties "may" (as opposed to "must") issue marriage licenses. So he's taking his county out of the marriage business.
Clearly, the government isn't a private business, and the judge's action amounts to using the law as an excuse to enshrine a form of institutional bias. But I have to give the judge credit for one thing: He understands the principle that it's all or nothing. If you offer a service to the general public, you must serve everyone in the general public equally. Your only alternative is to pack up your tent and go home - where you can eat that cake you refused to bake for that same-sex couple (if it isn't stale by the time you get there and doesn't aggravate your diabetes).
If you're in business to serve the general public, that includes people of both genders, of all races, creeds and sexual orientations. If you don't feel comfortable providing a service, stop providing that service ... to everyone. But don't pretend you have a problem with the service itself when your real issue is with the person on the other end - someone who has every right to live her own life independently without being told by some business she isn't good enough. If you think you can or should play a role in her life by limiting her options, that's your ego, not your ethics, talking.
And as I said, it's not about you.