I think people should be free to boycott such a company, just as Chik-fil-A has the right to be open about their Christianity, and just as how others have the right to pick their battles (and choose to continue to eat there). But there's an uncomfortable amount of guilt-tripping in this thread.
You mean "open about their homophobia," surely. It's not Christianity per se that people object to.
Otherwise we'd be boycotting In N Out too.