As a private business, its none of my or anyone's business what you decide to sell or not sell. I'm standing with you on that. However, it might be a different story for who you choose to hire and fire. I don't think it'd be acceptable to fire someone or not hire someone based on their religious preference, among other things. Although it would be strange if say an atheist or a Muslim was working at say a Christian bookstore for example. But I'd say as long as they don't insult or discriminate against the customers or other employees I think they have just as much right to work their as Christians, and the Christians working their being held to the same degree of respect of the other employees, etc.
But what you choose to sell? That's your business, literally.
Didn't watch the video as I'm on mobile data, but no we should not "ban religion" that's ridiculous.
Again, I think my opinions would line up pretty well with most atheists, though not all of course.