"Discrimination" seems to be an increasingly meaningless word. Treating people differently based on their superficial traits is bullshit and you're a terrible person if you do it, but people now use the word to cover non-superficial traits as well, such as religion. A person's religion is their choice and far from a morally irrelevant choice at that. Since religions make claims about how people should act, it's obvious that one religion can be morally better than another. And of course treating everyone "equally" is actually wrong if they're morally different. (Instead, we should treat everyone "according to the same rules".) So actually, it's not just acceptable but can even be admirable to refuse to do business with someone based on their religion, if you believe their religion is morally repulsive.
"Gender identity" is another thing that shouldn't be protected under anti-discrimination. People aren't born "identifying" as male or female or any third gender nonsense, they're born with biological facts that they have no reason to hide from and if they're going to ask me to use the wrong words to uphold their sexist attitudes, then no, I will not and I might refuse to do business with someone who engages in this.
Also "sexual orientation", because although people don't choose who they're attracted to, they do choose who they actually have sex with (and that's always what heteronormativists actually judge on, despite the strawman attempts of liberals). Of course, it still needs to be argued separately that having sex with someone of the same gender is immoral, and that's not even a position I hold, but I will argue to my last breath that it is different in kind from racism and sexism.