I'm very sympathetic to your point (I'm actually agnostic, so I tend to look at these issue through several lenses at the same time.) My take on the certainty of theism is that there's often better support for it than some will admit, but most of us don't see a slam-dunk case for it.
I do think you're missing one of my main points here, though. I agree that a certain form of harm is done to gay persons who are unable to get equivalent business accommodation for their weddings as do straight couples.
But my point was that Christians, and perhaps some other religious persons, also suffer a kind of harm: having to choose between committing acts that may be prohibited by their faith, and not being able to make their living.
I'm not arguing about a particular manner in which those two notions of harm should be balanced in public policy. I'm simply raising the point that it's not a simply matter of "harm A" vs. "no harm". To Christians, it's a matter of "harm A" vs. "harm B". Atheists, on the other hand, see it as "harm A" vs. "no harm". Or at last I think they do.
BTW, thanks for the civil discussion. You're raising good points in a friendly manner, which doesn't always happen. I really appreciate it.