We don't have to. It doesn't matter. Your rights stop when they impede upon the rights of others. Your right to swing your arms stops just before my nose.
If you hold a religious belief, that's find. If your religious belief leads you to enacting laws that impact me, or business practices that impact me, or anyone, you don't have that right. Sorry. Don't like it, there's fundamentalist countries out there that practice one religion you can move to. This country, however, was founded as a secular nation with a separation between church and state (to protect religions from other religions...like the Church of England being connected to government etc.).
I disagree with you that being gay is a choice, because it's not backed by science. Studies on gay populations hints to a complex codominant sex-linked recessive trait (appearing more in males...heterozygous females showing "bi" characteristics considerably higher than males etc...)
But even if it were a choice, religion is also a choice. Does that mean a store owner has the right to deny service to a non-christian because it's their sincerely held religious belief? But it's a choice isn't it? Oh wait...we actually have a law preventing that? But I thought it was a choice...and we can discrinate against people by the choices they make...
The accrobatics you guys have to do to justify this asinine horse crap public policy is just sad. We should just not discriminate against people period. Especially in things that aren't our business. If you have sincerely held religious beliefs, that's fine. But you're sincrely held religious beliefs stop when they potentially interfere with other people.
If you don't like that, don't live in America. Because that's what FREEDOM is. Freedom to not give a rat's ass about your beliefs, or be inconvenienced or impeded by them. I won't impede on your right to hold them, so long as you're not impeding on the rest of us.